diff --git a/packages/SystemUI/aconfig/systemui.aconfig b/packages/SystemUI/aconfig/systemui.aconfig
index c49ffb4..c1d8d55 100644
--- a/packages/SystemUI/aconfig/systemui.aconfig
+++ b/packages/SystemUI/aconfig/systemui.aconfig
@@ -1128,6 +1128,16 @@
 }
 
 flag {
+  name: "media_controls_umo_inflation_in_background"
+  namespace: "systemui"
+  description: "Inflate UMO in background thread"
+  bug: "368514198"
+  metadata {
+    purpose: PURPOSE_BUGFIX
+  }
+}
+
+flag {
   namespace: "systemui"
   name: "enable_view_capture_tracing"
   description: "Enables view capture tracing in System UI."
@@ -1431,4 +1441,4 @@
    metadata {
        purpose: PURPOSE_BUGFIX
    }
-}
\ No newline at end of file
+}
diff --git a/packages/SystemUI/src/com/android/systemui/media/controls/ui/controller/MediaCarouselController.kt b/packages/SystemUI/src/com/android/systemui/media/controls/ui/controller/MediaCarouselController.kt
index bb9517a..bbe3d24 100644
--- a/packages/SystemUI/src/com/android/systemui/media/controls/ui/controller/MediaCarouselController.kt
+++ b/packages/SystemUI/src/com/android/systemui/media/controls/ui/controller/MediaCarouselController.kt
@@ -16,6 +16,7 @@
 
 package com.android.systemui.media.controls.ui.controller
 
+import android.annotation.WorkerThread
 import android.app.PendingIntent
 import android.content.Context
 import android.content.Intent
@@ -41,6 +42,7 @@
 import com.android.keyguard.KeyguardUpdateMonitor
 import com.android.keyguard.KeyguardUpdateMonitorCallback
 import com.android.systemui.Dumpable
+import com.android.systemui.Flags.mediaControlsUmoInflationInBackground
 import com.android.systemui.dagger.SysUISingleton
 import com.android.systemui.dagger.qualifiers.Application
 import com.android.systemui.dagger.qualifiers.Background
@@ -136,7 +138,7 @@
     private val activityStarter: ActivityStarter,
     private val systemClock: SystemClock,
     @Main private val mainDispatcher: CoroutineDispatcher,
-    @Main executor: DelayableExecutor,
+    @Main private val uiExecutor: DelayableExecutor,
     @Background private val bgExecutor: Executor,
     @Background private val backgroundDispatcher: CoroutineDispatcher,
     private val mediaManager: MediaDataManager,
@@ -224,7 +226,7 @@
     private var carouselLocale: Locale? = null
 
     private val animationScaleObserver: ContentObserver =
-        object : ContentObserver(executor, 0) {
+        object : ContentObserver(uiExecutor, 0) {
             override fun onChange(selfChange: Boolean) {
                 if (!SceneContainerFlag.isEnabled) {
                     MediaPlayerData.players().forEach { it.updateAnimatorDurationScale() }
@@ -347,7 +349,7 @@
             MediaCarouselScrollHandler(
                 mediaCarousel,
                 pageIndicator,
-                executor,
+                uiExecutor,
                 this::onSwipeToDismiss,
                 this::updatePageIndicatorLocation,
                 this::updateSeekbarListening,
@@ -455,7 +457,17 @@
                     isSsReactivated: Boolean,
                 ) {
                     debugLogger.logMediaLoaded(key, data.active)
-                    if (addOrUpdatePlayer(key, oldKey, data, isSsReactivated)) {
+                    val onUiExecutionEnd =
+                        if (mediaControlsUmoInflationInBackground()) {
+                            Runnable {
+                                if (immediately) {
+                                    updateHostVisibility()
+                                }
+                            }
+                        } else {
+                            null
+                        }
+                    if (addOrUpdatePlayer(key, oldKey, data, isSsReactivated, onUiExecutionEnd)) {
                         // Log card received if a new resumable media card is added
                         MediaPlayerData.getMediaPlayer(key)?.let {
                             logSmartspaceCardReported(
@@ -970,6 +982,7 @@
         oldKey: String?,
         data: MediaData,
         isSsReactivated: Boolean,
+        onUiExecutionEnd: Runnable? = null,
     ): Boolean =
         traceSection("MediaCarouselController#addOrUpdatePlayer") {
             MediaPlayerData.moveIfExists(oldKey, key)
@@ -977,76 +990,119 @@
             val curVisibleMediaKey =
                 MediaPlayerData.visiblePlayerKeys()
                     .elementAtOrNull(mediaCarouselScrollHandler.visibleMediaIndex)
-            if (existingPlayer == null) {
-                val newPlayer = mediaControlPanelFactory.get()
-                if (SceneContainerFlag.isEnabled) {
-                    newPlayer.mediaViewController.widthInSceneContainerPx = widthInSceneContainerPx
-                    newPlayer.mediaViewController.heightInSceneContainerPx =
-                        heightInSceneContainerPx
-                }
-                newPlayer.attachPlayer(
-                    MediaViewHolder.create(LayoutInflater.from(context), mediaContent)
-                )
-                newPlayer.mediaViewController.sizeChangedListener = this::updateCarouselDimensions
-                val lp =
-                    LinearLayout.LayoutParams(
-                        ViewGroup.LayoutParams.MATCH_PARENT,
-                        ViewGroup.LayoutParams.WRAP_CONTENT,
-                    )
-                newPlayer.mediaViewHolder?.player?.setLayoutParams(lp)
-                newPlayer.bindPlayer(data, key)
-                newPlayer.setListening(
-                    mediaCarouselScrollHandler.visibleToUser && currentlyExpanded
-                )
-                MediaPlayerData.addMediaPlayer(
-                    key,
-                    data,
-                    newPlayer,
-                    systemClock,
-                    isSsReactivated,
-                    debugLogger,
-                )
-                updateViewControllerToState(newPlayer.mediaViewController, noAnimation = true)
-                // Media data added from a recommendation card should starts playing.
-                if (
-                    (shouldScrollToKey && data.isPlaying == true) ||
-                        (!shouldScrollToKey && data.active)
-                ) {
-                    reorderAllPlayers(curVisibleMediaKey, key)
+            if (mediaControlsUmoInflationInBackground()) {
+                if (existingPlayer == null) {
+                    bgExecutor.execute {
+                        val mediaViewHolder = createMediaViewHolderInBg()
+                        // Add the new player in the main thread.
+                        uiExecutor.execute {
+                            setupNewPlayer(
+                                key,
+                                data,
+                                isSsReactivated,
+                                curVisibleMediaKey,
+                                mediaViewHolder,
+                            )
+                            updatePageIndicator()
+                            mediaCarouselScrollHandler.onPlayersChanged()
+                            mediaFrame.requiresRemeasuring = true
+                            onUiExecutionEnd?.run()
+                        }
+                    }
                 } else {
-                    needsReordering = true
+                    updatePlayer(key, data, isSsReactivated, curVisibleMediaKey, existingPlayer)
+                    updatePageIndicator()
+                    mediaCarouselScrollHandler.onPlayersChanged()
+                    mediaFrame.requiresRemeasuring = true
+                    onUiExecutionEnd?.run()
                 }
             } else {
-                existingPlayer.bindPlayer(data, key)
-                MediaPlayerData.addMediaPlayer(
-                    key,
-                    data,
-                    existingPlayer,
-                    systemClock,
-                    isSsReactivated,
-                    debugLogger,
-                )
-                val packageName = MediaPlayerData.smartspaceMediaData?.packageName ?: String()
-                // In case of recommendations hits.
-                // Check the playing status of media player and the package name.
-                // To make sure we scroll to the right app's media player.
-                if (
-                    isReorderingAllowed ||
-                        shouldScrollToKey &&
-                            data.isPlaying == true &&
-                            packageName == data.packageName
-                ) {
-                    reorderAllPlayers(curVisibleMediaKey, key)
+                if (existingPlayer == null) {
+                    val mediaViewHolder =
+                        MediaViewHolder.create(LayoutInflater.from(context), mediaContent)
+                    setupNewPlayer(key, data, isSsReactivated, curVisibleMediaKey, mediaViewHolder)
                 } else {
-                    needsReordering = true
+                    updatePlayer(key, data, isSsReactivated, curVisibleMediaKey, existingPlayer)
                 }
+                updatePageIndicator()
+                mediaCarouselScrollHandler.onPlayersChanged()
+                mediaFrame.requiresRemeasuring = true
+                onUiExecutionEnd?.run()
             }
-            updatePageIndicator()
-            mediaCarouselScrollHandler.onPlayersChanged()
-            mediaFrame.requiresRemeasuring = true
             return existingPlayer == null
         }
 
+    private fun updatePlayer(
+        key: String,
+        data: MediaData,
+        isSsReactivated: Boolean,
+        curVisibleMediaKey: MediaPlayerData.MediaSortKey?,
+        existingPlayer: MediaControlPanel,
+    ) {
+        existingPlayer.bindPlayer(data, key)
+        MediaPlayerData.addMediaPlayer(
+            key,
+            data,
+            existingPlayer,
+            systemClock,
+            isSsReactivated,
+            debugLogger,
+        )
+        val packageName = MediaPlayerData.smartspaceMediaData?.packageName ?: String()
+        // In case of recommendations hits.
+        // Check the playing status of media player and the package name.
+        // To make sure we scroll to the right app's media player.
+        if (
+            isReorderingAllowed ||
+                shouldScrollToKey && data.isPlaying == true && packageName == data.packageName
+        ) {
+            reorderAllPlayers(curVisibleMediaKey, key)
+        } else {
+            needsReordering = true
+        }
+    }
+
+    private fun setupNewPlayer(
+        key: String,
+        data: MediaData,
+        isSsReactivated: Boolean,
+        curVisibleMediaKey: MediaPlayerData.MediaSortKey?,
+        mediaViewHolder: MediaViewHolder,
+    ) {
+        val newPlayer = mediaControlPanelFactory.get()
+        newPlayer.attachPlayer(mediaViewHolder)
+        newPlayer.mediaViewController.sizeChangedListener =
+            this@MediaCarouselController::updateCarouselDimensions
+        val lp =
+            LinearLayout.LayoutParams(
+                ViewGroup.LayoutParams.MATCH_PARENT,
+                ViewGroup.LayoutParams.WRAP_CONTENT,
+            )
+        newPlayer.mediaViewHolder?.player?.setLayoutParams(lp)
+        newPlayer.bindPlayer(data, key)
+        newPlayer.setListening(mediaCarouselScrollHandler.visibleToUser && currentlyExpanded)
+        MediaPlayerData.addMediaPlayer(
+            key,
+            data,
+            newPlayer,
+            systemClock,
+            isSsReactivated,
+            debugLogger,
+        )
+        updateViewControllerToState(newPlayer.mediaViewController, noAnimation = true)
+        // Media data added from a recommendation card should starts playing.
+        if ((shouldScrollToKey && data.isPlaying == true) || (!shouldScrollToKey && data.active)) {
+            reorderAllPlayers(curVisibleMediaKey, key)
+        } else {
+            needsReordering = true
+        }
+    }
+
+    @WorkerThread
+    private fun createMediaViewHolderInBg(): MediaViewHolder {
+        return MediaViewHolder.create(LayoutInflater.from(context), mediaContent)
+    }
+
     private fun addSmartspaceMediaRecommendations(
         key: String,
         data: SmartspaceMediaData,
@@ -1163,8 +1219,16 @@
         val previousVisibleKey =
             MediaPlayerData.visiblePlayerKeys()
                 .elementAtOrNull(mediaCarouselScrollHandler.visibleMediaIndex)
+        val onUiExecutionEnd = Runnable {
+            if (recreateMedia) {
+                reorderAllPlayers(previousVisibleKey)
+            }
+        }
 
-        MediaPlayerData.mediaData().forEach { (key, data, isSsMediaRec) ->
+        val mediaDataList = MediaPlayerData.mediaData()
+        // Do not loop through the original list of media data because the re-addition of media data
+        // is being executed in background thread.
+        mediaDataList.forEach { (key, data, isSsMediaRec) ->
             if (isSsMediaRec) {
                 val smartspaceMediaData = MediaPlayerData.smartspaceMediaData
                 removePlayer(key, dismissMediaData = false, dismissRecommendation = false)
@@ -1175,6 +1239,7 @@
                         MediaPlayerData.shouldPrioritizeSs,
                     )
                 }
+                onUiExecutionEnd.run()
             } else {
                 val isSsReactivated = MediaPlayerData.isSsReactivated(key)
                 if (recreateMedia) {
@@ -1185,11 +1250,9 @@
                     oldKey = null,
                     data = data,
                     isSsReactivated = isSsReactivated,
+                    onUiExecutionEnd = onUiExecutionEnd,
                 )
             }
-            if (recreateMedia) {
-                reorderAllPlayers(previousVisibleKey)
-            }
         }
     }
 
diff --git a/packages/SystemUI/src/com/android/systemui/media/controls/ui/controller/MediaHostStatesManager.kt b/packages/SystemUI/src/com/android/systemui/media/controls/ui/controller/MediaHostStatesManager.kt
index 8660d12..782da4b 100644
--- a/packages/SystemUI/src/com/android/systemui/media/controls/ui/controller/MediaHostStatesManager.kt
+++ b/packages/SystemUI/src/com/android/systemui/media/controls/ui/controller/MediaHostStatesManager.kt
@@ -17,6 +17,7 @@
 package com.android.systemui.media.controls.ui.controller
 
 import com.android.app.tracing.traceSection
+import com.android.systemui.Flags.mediaControlsUmoInflationInBackground
 import com.android.systemui.dagger.SysUISingleton
 import com.android.systemui.media.controls.ui.view.MediaHostState
 import com.android.systemui.util.animation.MeasurementOutput
@@ -71,23 +72,34 @@
      */
     fun updateCarouselDimensions(
         @MediaLocation location: Int,
-        hostState: MediaHostState
+        hostState: MediaHostState,
     ): MeasurementOutput =
         traceSection("MediaHostStatesManager#updateCarouselDimensions") {
             val result = MeasurementOutput(0, 0)
+            var changed = false
             for (controller in controllers) {
                 val measurement = controller.getMeasurementsForState(hostState)
                 measurement?.let {
                     if (it.measuredHeight > result.measuredHeight) {
                         result.measuredHeight = it.measuredHeight
+                        changed = true
                     }
                     if (it.measuredWidth > result.measuredWidth) {
                         result.measuredWidth = it.measuredWidth
+                        changed = true
                     }
                 }
             }
-            carouselSizes[location] = result
-            return result
+            if (mediaControlsUmoInflationInBackground()) {
+                // Set carousel size if result measurements changed. This avoids setting carousel
+                // size when this method gets called before the addition of media view controllers
+                if (!carouselSizes.contains(location) || changed) {
+                    carouselSizes[location] = result
+                }
+            } else {
+                carouselSizes[location] = result
+            }
+            return carouselSizes[location] ?: result
         }
 
     /** Add a callback to be called when a MediaState has updated */
diff --git a/packages/SystemUI/src/com/android/systemui/media/controls/ui/view/MediaHost.kt b/packages/SystemUI/src/com/android/systemui/media/controls/ui/view/MediaHost.kt
index 09a6181..5ddc347 100644
--- a/packages/SystemUI/src/com/android/systemui/media/controls/ui/view/MediaHost.kt
+++ b/packages/SystemUI/src/com/android/systemui/media/controls/ui/view/MediaHost.kt
@@ -20,6 +20,7 @@
 import android.util.ArraySet
 import android.view.View
 import android.view.View.OnAttachStateChangeListener
+import com.android.systemui.Flags.mediaControlsUmoInflationInBackground
 import com.android.systemui.media.controls.domain.pipeline.MediaDataManager
 import com.android.systemui.media.controls.shared.model.MediaData
 import com.android.systemui.media.controls.shared.model.SmartspaceMediaData
@@ -91,8 +92,10 @@
                 data: MediaData,
                 immediately: Boolean,
                 receivedSmartspaceCardLatency: Int,
-                isSsReactivated: Boolean
+                isSsReactivated: Boolean,
             ) {
+                if (mediaControlsUmoInflationInBackground()) return
+
                 if (immediately) {
                     updateViewVisibility()
                 }
@@ -101,7 +104,7 @@
             override fun onSmartspaceMediaDataLoaded(
                 key: String,
                 data: SmartspaceMediaData,
-                shouldPrioritize: Boolean
+                shouldPrioritize: Boolean,
             ) {
                 updateViewVisibility()
             }
@@ -171,7 +174,7 @@
                         input.widthMeasureSpec =
                             View.MeasureSpec.makeMeasureSpec(
                                 View.MeasureSpec.getSize(input.widthMeasureSpec),
-                                View.MeasureSpec.EXACTLY
+                                View.MeasureSpec.EXACTLY,
                             )
                     }
                     // This will trigger a state change that ensures that we now have a state
diff --git a/packages/SystemUI/tests/src/com/android/systemui/media/controls/ui/controller/MediaCarouselControllerTest.kt b/packages/SystemUI/tests/src/com/android/systemui/media/controls/ui/controller/MediaCarouselControllerTest.kt
index 03667cf..570c640 100644
--- a/packages/SystemUI/tests/src/com/android/systemui/media/controls/ui/controller/MediaCarouselControllerTest.kt
+++ b/packages/SystemUI/tests/src/com/android/systemui/media/controls/ui/controller/MediaCarouselControllerTest.kt
@@ -21,19 +21,19 @@
 import android.content.res.Configuration
 import android.database.ContentObserver
 import android.os.LocaleList
+import android.platform.test.flag.junit.FlagsParameterization
 import android.provider.Settings
 import android.testing.TestableLooper
 import android.util.MathUtils.abs
 import android.view.View
-import androidx.test.ext.junit.runners.AndroidJUnit4
 import androidx.test.filters.SmallTest
 import com.android.compose.animation.scene.ObservableTransitionState
 import com.android.compose.animation.scene.SceneKey
 import com.android.internal.logging.InstanceId
 import com.android.keyguard.KeyguardUpdateMonitor
 import com.android.keyguard.KeyguardUpdateMonitorCallback
+import com.android.systemui.Flags.mediaControlsUmoInflationInBackground
 import com.android.systemui.SysuiTestCase
-import com.android.systemui.dagger.qualifiers.Main
 import com.android.systemui.deviceentry.domain.interactor.deviceEntryInteractor
 import com.android.systemui.dump.DumpManager
 import com.android.systemui.flags.DisableSceneContainer
@@ -71,7 +71,6 @@
 import com.android.systemui.statusbar.notification.collection.provider.VisualStabilityProvider
 import com.android.systemui.statusbar.policy.ConfigurationController
 import com.android.systemui.testKosmos
-import com.android.systemui.util.concurrency.DelayableExecutor
 import com.android.systemui.util.concurrency.FakeExecutor
 import com.android.systemui.util.settings.GlobalSettings
 import com.android.systemui.util.settings.unconfinedDispatcherFakeSettings
@@ -106,6 +105,8 @@
 import org.mockito.kotlin.any
 import org.mockito.kotlin.capture
 import org.mockito.kotlin.eq
+import platform.test.runner.parameterized.ParameterizedAndroidJunit4
+import platform.test.runner.parameterized.Parameters
 
 private val DATA = MediaTestUtils.emptyMediaData
 
@@ -116,8 +117,8 @@
 @ExperimentalCoroutinesApi
 @SmallTest
 @TestableLooper.RunWithLooper(setAsMainLooper = true)
-@RunWith(AndroidJUnit4::class)
-class MediaCarouselControllerTest : SysuiTestCase() {
+@RunWith(ParameterizedAndroidJunit4::class)
+class MediaCarouselControllerTest(flags: FlagsParameterization) : SysuiTestCase() {
     private val kosmos = testKosmos()
     private val testDispatcher = kosmos.unconfinedTestDispatcher
     private val secureSettings = kosmos.unconfinedDispatcherFakeSettings
@@ -129,7 +130,6 @@
     @Mock lateinit var mediaHostStatesManager: MediaHostStatesManager
     @Mock lateinit var mediaHostState: MediaHostState
     @Mock lateinit var activityStarter: ActivityStarter
-    @Mock @Main private lateinit var executor: DelayableExecutor
     @Mock lateinit var mediaDataManager: MediaDataManager
     @Mock lateinit var configurationController: ConfigurationController
     @Mock lateinit var falsingManager: FalsingManager
@@ -153,16 +153,33 @@
 
     private val clock = FakeSystemClock()
     private lateinit var bgExecutor: FakeExecutor
+    private lateinit var uiExecutor: FakeExecutor
     private lateinit var mediaCarouselController: MediaCarouselController
 
     private var originalResumeSetting =
         Settings.Secure.getInt(context.contentResolver, Settings.Secure.MEDIA_CONTROLS_RESUME, 1)
 
+    companion object {
+        @JvmStatic
+        @Parameters(name = "{0}")
+        fun getParams(): List<FlagsParameterization> {
+            return FlagsParameterization.progressionOf(
+                com.android.systemui.Flags.FLAG_MEDIA_CONTROLS_UMO_INFLATION_IN_BACKGROUND
+            )
+        }
+    }
+
+    init {
+        mSetFlagsRule.setFlagsParameterization(flags)
+    }
+
     @Before
     fun setup() {
         MockitoAnnotations.initMocks(this)
         context.resources.configuration.setLocales(LocaleList(Locale.US, Locale.UK))
         bgExecutor = FakeExecutor(clock)
+        uiExecutor = FakeExecutor(clock)
+
         mediaCarouselController =
             MediaCarouselController(
                 applicationScope = kosmos.applicationCoroutineScope,
@@ -173,7 +190,7 @@
                 activityStarter = activityStarter,
                 systemClock = clock,
                 mainDispatcher = kosmos.testDispatcher,
-                executor = executor,
+                uiExecutor = uiExecutor,
                 bgExecutor = bgExecutor,
                 backgroundDispatcher = testDispatcher,
                 mediaManager = mediaDataManager,
@@ -201,10 +218,11 @@
         whenever(mediaFlags.isPersistentSsCardEnabled()).thenReturn(false)
         MediaPlayerData.clear()
         FakeExecutor.exhaustExecutors(bgExecutor)
+        FakeExecutor.exhaustExecutors(uiExecutor)
         verify(globalSettings)
             .registerContentObserverSync(
                 eq(Settings.Global.getUriFor(Settings.Global.ANIMATOR_DURATION_SCALE)),
-                capture(settingsObserverCaptor)
+                capture(settingsObserverCaptor),
             )
     }
 
@@ -213,7 +231,7 @@
         Settings.Secure.putInt(
             context.contentResolver,
             Settings.Secure.MEDIA_CONTROLS_RESUME,
-            originalResumeSetting
+            originalResumeSetting,
         )
     }
 
@@ -227,9 +245,9 @@
                     active = true,
                     isPlaying = true,
                     playbackLocation = MediaData.PLAYBACK_LOCAL,
-                    resumption = false
+                    resumption = false,
                 ),
-                4500L
+                4500L,
             )
 
         val playingCast =
@@ -239,9 +257,9 @@
                     active = true,
                     isPlaying = true,
                     playbackLocation = MediaData.PLAYBACK_CAST_LOCAL,
-                    resumption = false
+                    resumption = false,
                 ),
-                5000L
+                5000L,
             )
 
         val pausedLocal =
@@ -251,9 +269,9 @@
                     active = true,
                     isPlaying = false,
                     playbackLocation = MediaData.PLAYBACK_LOCAL,
-                    resumption = false
+                    resumption = false,
                 ),
-                1000L
+                1000L,
             )
 
         val pausedCast =
@@ -263,9 +281,9 @@
                     active = true,
                     isPlaying = false,
                     playbackLocation = MediaData.PLAYBACK_CAST_LOCAL,
-                    resumption = false
+                    resumption = false,
                 ),
-                2000L
+                2000L,
             )
 
         val playingRcn =
@@ -275,9 +293,9 @@
                     active = true,
                     isPlaying = true,
                     playbackLocation = MediaData.PLAYBACK_CAST_REMOTE,
-                    resumption = false
+                    resumption = false,
                 ),
-                5000L
+                5000L,
             )
 
         val pausedRcn =
@@ -287,9 +305,9 @@
                     active = true,
                     isPlaying = false,
                     playbackLocation = MediaData.PLAYBACK_CAST_REMOTE,
-                    resumption = false
+                    resumption = false,
                 ),
-                5000L
+                5000L,
             )
 
         val active =
@@ -299,9 +317,9 @@
                     active = true,
                     isPlaying = false,
                     playbackLocation = MediaData.PLAYBACK_LOCAL,
-                    resumption = true
+                    resumption = true,
                 ),
-                250L
+                250L,
             )
 
         val resume1 =
@@ -311,9 +329,9 @@
                     active = false,
                     isPlaying = false,
                     playbackLocation = MediaData.PLAYBACK_LOCAL,
-                    resumption = true
+                    resumption = true,
                 ),
-                500L
+                500L,
             )
 
         val resume2 =
@@ -323,9 +341,9 @@
                     active = false,
                     isPlaying = false,
                     playbackLocation = MediaData.PLAYBACK_LOCAL,
-                    resumption = true
+                    resumption = true,
                 ),
-                1000L
+                1000L,
             )
 
         val activeMoreRecent =
@@ -336,9 +354,9 @@
                     isPlaying = false,
                     playbackLocation = MediaData.PLAYBACK_LOCAL,
                     resumption = true,
-                    lastActive = 2L
+                    lastActive = 2L,
                 ),
-                1000L
+                1000L,
             )
 
         val activeLessRecent =
@@ -349,9 +367,9 @@
                     isPlaying = false,
                     playbackLocation = MediaData.PLAYBACK_LOCAL,
                     resumption = true,
-                    lastActive = 1L
+                    lastActive = 1L,
                 ),
-                1000L
+                1000L,
             )
         // Expected ordering for media players:
         // Actively playing local sessions
@@ -370,7 +388,7 @@
                 pausedRcn,
                 active,
                 resume2,
-                resume1
+                resume1,
             )
 
         expected.forEach {
@@ -380,7 +398,7 @@
                 it.second.copy(notificationKey = it.first),
                 panel,
                 clock,
-                isSsReactivated = false
+                isSsReactivated = false,
             )
         }
 
@@ -403,7 +421,7 @@
             EMPTY_SMARTSPACE_MEDIA_DATA.copy(isActive = true),
             panel,
             true,
-            clock
+            clock,
         )
 
         // Then it should be shown immediately after any actively playing controls
@@ -421,7 +439,7 @@
         listener.value.onSmartspaceMediaDataLoaded(
             SMARTSPACE_KEY,
             EMPTY_SMARTSPACE_MEDIA_DATA.copy(isActive = true),
-            true
+            true,
         )
 
         // Then it should be shown immediately after any actively playing controls
@@ -439,7 +457,7 @@
             EMPTY_SMARTSPACE_MEDIA_DATA.copy(isActive = true),
             panel,
             false,
-            clock
+            clock,
         )
 
         // Then it should be shown at the end of the carousel's active entries
@@ -461,8 +479,8 @@
                 active = true,
                 isPlaying = true,
                 playbackLocation = MediaData.PLAYBACK_LOCAL,
-                resumption = false
-            )
+                resumption = false,
+            ),
         )
         listener.value.onMediaDataLoaded(
             PLAYING_LOCAL,
@@ -471,19 +489,20 @@
                 active = true,
                 isPlaying = false,
                 playbackLocation = MediaData.PLAYBACK_LOCAL,
-                resumption = true
-            )
+                resumption = true,
+            ),
         )
+        runAllReady()
 
         assertEquals(
             MediaPlayerData.getMediaPlayerIndex(PAUSED_LOCAL),
-            mediaCarouselController.mediaCarouselScrollHandler.visibleMediaIndex
+            mediaCarouselController.mediaCarouselScrollHandler.visibleMediaIndex,
         )
         // paused player order should stays the same in visibleMediaPLayer map.
         // paused player order should be first in mediaPlayer map.
         assertEquals(
             MediaPlayerData.visiblePlayerKeys().elementAt(3),
-            MediaPlayerData.playerKeys().elementAt(0)
+            MediaPlayerData.playerKeys().elementAt(0),
         )
     }
 
@@ -506,7 +525,7 @@
         mediaCarouselController.onDesiredLocationChanged(
             LOCATION_QS,
             mediaHostState,
-            animate = false
+            animate = false,
         )
         bgExecutor.runAllReady()
         verify(logger).logCarouselPosition(LOCATION_QS)
@@ -517,7 +536,7 @@
         mediaCarouselController.onDesiredLocationChanged(
             MediaHierarchyManager.LOCATION_QQS,
             mediaHostState,
-            animate = false
+            animate = false,
         )
         bgExecutor.runAllReady()
         verify(logger).logCarouselPosition(MediaHierarchyManager.LOCATION_QQS)
@@ -528,7 +547,7 @@
         mediaCarouselController.onDesiredLocationChanged(
             MediaHierarchyManager.LOCATION_LOCKSCREEN,
             mediaHostState,
-            animate = false
+            animate = false,
         )
         bgExecutor.runAllReady()
         verify(logger).logCarouselPosition(MediaHierarchyManager.LOCATION_LOCKSCREEN)
@@ -539,7 +558,7 @@
         mediaCarouselController.onDesiredLocationChanged(
             MediaHierarchyManager.LOCATION_DREAM_OVERLAY,
             mediaHostState,
-            animate = false
+            animate = false,
         )
         bgExecutor.runAllReady()
         verify(logger).logCarouselPosition(MediaHierarchyManager.LOCATION_DREAM_OVERLAY)
@@ -570,8 +589,8 @@
                 active = true,
                 isPlaying = true,
                 playbackLocation = MediaData.PLAYBACK_LOCAL,
-                resumption = false
-            )
+                resumption = false,
+            ),
         )
         listener.value.onMediaDataLoaded(
             PAUSED_LOCAL,
@@ -580,14 +599,15 @@
                 active = true,
                 isPlaying = false,
                 playbackLocation = MediaData.PLAYBACK_LOCAL,
-                resumption = false
-            )
+                resumption = false,
+            ),
         )
+        runAllReady()
         // adding a media recommendation card.
         listener.value.onSmartspaceMediaDataLoaded(
             SMARTSPACE_KEY,
             EMPTY_SMARTSPACE_MEDIA_DATA,
-            false
+            false,
         )
         mediaCarouselController.shouldScrollToKey = true
         // switching between media players.
@@ -598,8 +618,8 @@
                 active = true,
                 isPlaying = false,
                 playbackLocation = MediaData.PLAYBACK_LOCAL,
-                resumption = true
-            )
+                resumption = true,
+            ),
         )
         listener.value.onMediaDataLoaded(
             PAUSED_LOCAL,
@@ -608,13 +628,14 @@
                 active = true,
                 isPlaying = true,
                 playbackLocation = MediaData.PLAYBACK_LOCAL,
-                resumption = false
-            )
+                resumption = false,
+            ),
         )
+        runAllReady()
 
         assertEquals(
             MediaPlayerData.getMediaPlayerIndex(PAUSED_LOCAL),
-            mediaCarouselController.mediaCarouselScrollHandler.visibleMediaIndex
+            mediaCarouselController.mediaCarouselScrollHandler.visibleMediaIndex,
         )
     }
 
@@ -626,7 +647,7 @@
         listener.value.onSmartspaceMediaDataLoaded(
             SMARTSPACE_KEY,
             EMPTY_SMARTSPACE_MEDIA_DATA.copy(packageName = "PACKAGE_NAME", isActive = true),
-            false
+            false,
         )
         listener.value.onMediaDataLoaded(
             PLAYING_LOCAL,
@@ -635,14 +656,15 @@
                 active = true,
                 isPlaying = true,
                 playbackLocation = MediaData.PLAYBACK_LOCAL,
-                resumption = false
-            )
+                resumption = false,
+            ),
         )
+        runAllReady()
 
         var playerIndex = MediaPlayerData.getMediaPlayerIndex(PLAYING_LOCAL)
         assertEquals(
             playerIndex,
-            mediaCarouselController.mediaCarouselScrollHandler.visibleMediaIndex
+            mediaCarouselController.mediaCarouselScrollHandler.visibleMediaIndex,
         )
         assertEquals(playerIndex, 0)
 
@@ -657,9 +679,10 @@
                 isPlaying = true,
                 playbackLocation = MediaData.PLAYBACK_LOCAL,
                 resumption = false,
-                packageName = "PACKAGE_NAME"
-            )
+                packageName = "PACKAGE_NAME",
+            ),
         )
+        runAllReady()
         playerIndex = MediaPlayerData.getMediaPlayerIndex(PLAYING_LOCAL)
         assertEquals(playerIndex, 0)
     }
@@ -704,7 +727,7 @@
             player1.second.copy(notificationKey = player1.first),
             panel,
             clock,
-            isSsReactivated = false
+            isSsReactivated = false,
         )
 
         assertEquals(mediaCarouselController.getCurrentVisibleMediaContentIntent(), clickIntent1)
@@ -717,7 +740,7 @@
             player2.second.copy(notificationKey = player2.first),
             panel,
             clock,
-            isSsReactivated = false
+            isSsReactivated = false,
         )
 
         // mediaCarouselScrollHandler.visibleMediaIndex is unchanged (= 0), and the new player is
@@ -732,7 +755,7 @@
             player3.second.copy(notificationKey = player3.first),
             panel,
             clock,
-            isSsReactivated = false
+            isSsReactivated = false,
         )
 
         // mediaCarouselScrollHandler.visibleMediaIndex is unchanged (= 0), and the new player is
@@ -822,7 +845,7 @@
         listener.value.onSmartspaceMediaDataLoaded(
             SMARTSPACE_KEY,
             EMPTY_SMARTSPACE_MEDIA_DATA.copy(isActive = true),
-            true
+            true,
         )
 
         // Then the carousel is updated
@@ -841,7 +864,7 @@
         listener.value.onSmartspaceMediaDataLoaded(
             SMARTSPACE_KEY,
             EMPTY_SMARTSPACE_MEDIA_DATA,
-            false
+            false,
         )
 
         // Then it is added to the carousel with correct state
@@ -886,7 +909,7 @@
             transitionRepository.sendTransitionSteps(
                 from = KeyguardState.LOCKSCREEN,
                 to = KeyguardState.GONE,
-                this
+                this,
             )
 
             verify(mediaCarousel).visibility = View.VISIBLE
@@ -932,7 +955,7 @@
             transitionRepository.sendTransitionSteps(
                 from = KeyguardState.GONE,
                 to = KeyguardState.LOCKSCREEN,
-                this
+                this,
             )
 
             assertEquals(true, updatedVisibility)
@@ -961,7 +984,7 @@
             transitionRepository.sendTransitionSteps(
                 from = KeyguardState.GONE,
                 to = KeyguardState.LOCKSCREEN,
-                this
+                this,
             )
 
             assertEquals(true, updatedVisibility)
@@ -1125,12 +1148,14 @@
         Settings.Secure.putInt(context.contentResolver, Settings.Secure.MEDIA_CONTROLS_RESUME, 0)
         val pausedMedia = DATA.copy(isPlaying = false)
         listener.value.onMediaDataLoaded(PAUSED_LOCAL, PAUSED_LOCAL, pausedMedia)
+        runAllReady()
         mediaCarouselController.onSwipeToDismiss()
 
         // When it can be removed immediately on update
         whenever(visualStabilityProvider.isReorderingAllowed).thenReturn(true)
         val inactiveMedia = pausedMedia.copy(active = false)
         listener.value.onMediaDataLoaded(PAUSED_LOCAL, PAUSED_LOCAL, inactiveMedia)
+        runAllReady()
 
         // This is processed as a user-initiated dismissal
         verify(debugLogger).logMediaRemoved(eq(PAUSED_LOCAL), eq(true))
@@ -1148,12 +1173,14 @@
 
         val pausedMedia = DATA.copy(isPlaying = false)
         listener.value.onMediaDataLoaded(PAUSED_LOCAL, PAUSED_LOCAL, pausedMedia)
+        runAllReady()
         mediaCarouselController.onSwipeToDismiss()
 
         // When it can't be removed immediately on update
         whenever(visualStabilityProvider.isReorderingAllowed).thenReturn(false)
         val inactiveMedia = pausedMedia.copy(active = false)
         listener.value.onMediaDataLoaded(PAUSED_LOCAL, PAUSED_LOCAL, inactiveMedia)
+        runAllReady()
         visualStabilityCallback.value.onReorderingAllowed()
 
         // This is processed as a user-initiated dismissal
@@ -1175,8 +1202,8 @@
                 active = true,
                 isPlaying = true,
                 playbackLocation = MediaData.PLAYBACK_LOCAL,
-                resumption = false
-            )
+                resumption = false,
+            ),
         )
         listener.value.onMediaDataLoaded(
             PAUSED_LOCAL,
@@ -1185,18 +1212,20 @@
                 active = true,
                 isPlaying = false,
                 playbackLocation = MediaData.PLAYBACK_LOCAL,
-                resumption = false
-            )
+                resumption = false,
+            ),
         )
+        runAllReady()
 
         val playersSize = MediaPlayerData.players().size
         reset(pageIndicator)
         function()
+        runAllReady()
 
         assertEquals(playersSize, MediaPlayerData.players().size)
         assertEquals(
             MediaPlayerData.getMediaPlayerIndex(PLAYING_LOCAL),
-            mediaCarouselController.mediaCarouselScrollHandler.visibleMediaIndex
+            mediaCarouselController.mediaCarouselScrollHandler.visibleMediaIndex,
         )
     }
 
@@ -1225,4 +1254,11 @@
         )
         runCurrent()
     }
+
+    private fun runAllReady() {
+        if (mediaControlsUmoInflationInBackground()) {
+            bgExecutor.runAllReady()
+            uiExecutor.runAllReady()
+        }
+    }
 }