When an item is partially downloaded, it shows as available, but it restarts plex app instead of playing.
When you finish watching an item, on the downloads it will show as watched, but on the main library it would still shows as if it’s still being played, with several minutes still remaining.
Sometimes after some minutes playing a downloaded item, screen goes black and you can hear parts of the beginning of the video. After some seconds it’s fixed and the item will resume playing fine, just without the part that was replaced with the black screen and the beginning sound.