Photo Albums - Poster Art

I love PLEX, but one thing continues to frustrate me - photo albums. I like to view my albums by folder (vs Timeline). I have added poster art (usually a photo from the folder itself) to each album but after a few days the poster “vanishes” leaving a black space in it’s place until I re-add a new poster. After trial and error I find the poster art vanishes after I run an update, optimize the database or clean old bundles. But the only poster art that disappears are the ones I’ve manually selected using the EDIT feature from the web application. The remaining poster art that PLEX randomly selects remains. Further frustration - the missing poster images isn’t consistent from one application to the other. For example, tonight I’m viewing a photo album via the web app on my Mac. There are five missing poster images. But when I view the same album on my PC or the mobile app the poster images are still there. But often they are missing from these platforms too. Any help?

It’s a commonly-ignored problem. I reported it some time ago.