[Motion] Unloaded ImageView when returning from MaterialContainerTransform

Description:
I'm using MaterialContainerTransform to transition from Fragment A, to a Fragment B that contains a RecyclerView whose items have ShapeableImageViews. Note: Fragment A is part of a ViewPager2, hosted by Fragment Z.

Transitionning from A to B works fine: transition is postponed until B's RecyclerView display is ready.
But when returning from B, we notice that images (that are loaded with Glide) are reset and blank.

Expected behavior:
Images loaded into ImageViews should not be reset ; those should be preserved in the return transition.
Also, why is SheapeableImageView showing black rounded corners ? This strange behavior of ShapeableImageView is also noticeable on Android Studio's layout preview (corners are then light grey).

Source code:

In Fragment Z:

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
  super.onViewCreated(view, savedInstanceState)
  postponeEnterTransition(1000, TimeUnit.MILLISECONDS)
  // Configure ViewPager adapter...
}

In Fragment A:

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
  super.onViewCreated(view, savedInstanceState)
  // Some view initialization code [...]
  viewModel.liveData.observe(viewLifecycleOwner) {
    adapter.submitList(it)
    val fragmentZ = requireParentFragment()
    fragmentZ.requireView().parent?.doOnPreDraw {
      fragmentZ.startPostponedEnterTransition()
    }
  }
}

private fun displayFragmentB() {
  // Root item view from the clicked element in RecyclerView. Has transitionName set in onBindViewHolder
  val itemView = ...
  val sharedElementExtras = FragmentNavigatortExtras(itemView to "some_item_id")
  requireParentFragment().apply {
    exitTransition = Hold().apply {
      duration = 300
      addTarget(R.id.fragment_z)
    }
    // Reset transition set by other navigation events
    reenterTransition = null
  }

  findNavController().navigate(R.id.to_fragment_b, sharedElementExtras)
}

In Fragment B:

override fun onCreate(savedInstanceState: Bundle?) {
  super.onCreate(savedInstanceState)

  sharedElementEnterTransition = MaterialContainerTransform().apply {
    drawingViewId = R.id.nav_host_fragment
    duration = 300
    scrimColor = Color.TRANSPARENT
    setAllContainerColors(themeColorSurface)
  }
}

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
  super.onViewCreated(view, savedInstanceState)

  postponeEnterTransition(500, TimeUnit.MILLISECONDS)
  view.transitionName = "some_item_id"

  viewModel.liveData.observe(viewLifecycleOwner) {
    adapter.submitList(it)
    view.parent?.doOnPreDraw {
      startPostponedEnterTransition()
    }
  }
}

Android API version: 29 (Q)

Material Library version: 1.2.1

Device: Nokia 7.1, but also encountered on emulator.

Inizia con gli snippet di transizione di Fragment A, B e Z e riproduci la navigazione di ritorno su Android API 29 usando MaterialContainerTransform, RecyclerView, ImageViews caricate da Glide e ShapeableImageView. Confronta la transizione di ritorno con le immagini vuote e gli angoli arrotondati neri segnalati; il lavoro è completato quando le immagini rimangono visibili e il rendering degli angoli è spiegato o corretto.