Crossposting here too since I feel like no Plex employee cares whatsoever about these issues:
This issue on collections have been brought up multiple times on this Plex forum as well as other forums like Reddit.
Titles in a manual collection and the collections themselves simply do not load on Android mobile. Just a black screen and ‘Uh oh… something is wrong’. The same items load in every other Plex app, and loads without issue in the old Plex Android app.
I would be 100% fine with the old Android app, but there is no way on Android just to pause updates for a single app.