server Version 1.24.0.4930
I updated Plex on my Android TV yesterday. Video thumbnail previews stopped working. I thought it was on the server side and restored database backups, rescanned all libraries, re-analyzed all, refreshed all metadata, optimized database, cleaned bundles.
I opened up Plex on my iPhone and the thumbnail previews work fine. The behavior with the Android app is this. I open a play list & shuffle. It shows previews for the first video correctly. Thereafter, when I fast forward (using the bar not 30 second skip), no matter how far down the shuffle I go, it continuously uses the thumbnail previews from the very first video for all subsequent videos.
I additionally reset my Nebula Capsule Max to factory default, installed & updated everything again & same behavior.
Edit: The thumbnail previews work on an individual video. If you play/shuffle any playlist or any folder, you will get thumbnail previews for the of the video for every subsequent video in the playlist/folder.
Looking through the forums, this may be related to auto-play issues other users are having in these threads: