Android Auto media browser not drawing root icons for Media3 app after January update

Question

Since the January Android Auto update, which updated the main media browser screen, the media browser interface has stopped displaying the library root child icons - the icons at the very top of the browser screen. I'm developing a Media3-ExoPlayer-based media app, and am using the following code to assign an icon to the media items. This worked fine for both root items and "regular" media items until the January update; after the update, "regular" items have the icons displayed, but not the top root items - the root items just show a white outline of the clipping region of the icon image.

MediaMetadata metaData;
MediaMetadata.Builder metaDataBuilder;
MediaItem.Builder mediaItemBuilder;

metaDataBuilder = new MediaMetadata.Builder();
metaDataBuilder.setTitle("Favorites");
metaDataBuilder.setMediaType(MediaMetadata.MEDIA_TYPE_FOLDER_PLAYLISTS);
metaDataBuilder.setArtworkUri(Uri.parse("android.resource://" + getPackageName(this.getClass()) + "/" + R.drawable.playlist));
metaDataBuilder.setIsBrowsable(true);
metaDataBuilder.setIsPlayable(false);
metaData = metaDataBuilder.build();

mediaItemBuilder = new MediaItem.Builder();
mediaItemBuilder.setMediaMetadata(metaData);
mediaItemBuilder.setMediaId(listName);
mediaItem = mediaItemBuilder.build();

This is occurring with both the DHU (desktop head unit used during development), and on an actual car (Toyota Highlander). I've tried different image formats (png, xml) and with multiple screen resolutions, to no avail. Should I be doing something else, or is this a known bug with the Android Auto update?