What version of iOS are you using? Is this about Plex on an iPhone or iPad?
Any particular details about filters/sorting you have applied when this happens?
I’ve tested this on my iPhone with iOS 13.4 and Plex for iOS 6.10 and cannot reproduce the described behavior.
I’m new and cannot figure out how to post a new topic. But this is another bug I found: in the iOS Plex app 6.11.1:
If you are viewing albums (music>artist>albums) in grid view with exactly 51 albums, the last one shows up as a grey box that cannot be opened.