Android emulator not receiving media button callbacks

Question

I have installed the app on my phone and the callbacks executing as intended when pressing the button on my headset, but on the emulator it does nothing.

The media button presses are generated with this code:

adb shell input keyevent 126

Interestingly I can stop outgoing calls with this command.

I even found in the Logcat's output the button press logs:

I/Input: injectKeyEvent: KeyEvent { action=ACTION_DOWN, keyCode=KEYCODE_MEDIA_PLAY, scanCode=0, metaState=0, flags=0x0, repeatCount=0, eventTime=46647423, downTime=46647423, deviceId=-1, source=0x101 }
I/Input: injectKeyEvent: KeyEvent { action=ACTION_UP, keyCode=KEYCODE_MEDIA_PLAY, scanCode=0, metaState=0, flags=0x0, repeatCount=0, eventTime=46647423, downTime=46647423, deviceId=-1, source=0x101 }

Code that creates the MediaSession:

val callback = object : MediaSession.Callback() {
        override fun onPlay() = pressCounter.press()
        override fun onPause() = pressCounter.press()
        override fun onStop() = pressCounter.press()
    }

    mediaSession = MediaSession(applicationContext, "MYMS")

    mediaSession.setCallback(callback)
    mediaSession.setPlaybackState(
            PlaybackState.Builder().setActions(PlaybackState.ACTION_PLAY or
                    PlaybackState.ACTION_PAUSE or
                    PlaybackState.ACTION_PLAY_PAUSE)
                    .setState(PlaybackState.STATE_PLAYING,
                            0,
                            1f).build())
    mediaSession.isActive = true