I have been exploring the collections feature more lately, however I noticed that most of my collections are randomly dropping items out of the collection. This happens with my manually-created collections, as I do not utilize smart collections.
For example: I had a collection for the Fast and Furious saga, which initially included all 9 movies. As it currently sits, there are only 5 movies in the collection, and I did not remove the missing 4.
Usually this indicates there’s some bad combination of events / settings.
If your server is configured to automatically / periodically scan your files and to empty its trash after every scan it can happen that Plex drops items from your library if the storage doesn’t react fast enough (e.g. slow to spin up) — while being online to scan some of your files. During a subsequent scan, the items will be recognized and re-added to your library.
If such a bad scan can happen for you, I strongly recommend to disable automatically emptying the server’s trash.
This way Plex will keep the library items (incl. all your manual edits like collection assignments)
So I did modify the scheduled tasks and I’ll see if anything changes. I have noticed though that they appear to remove from a collection after a metadata refresh. I’m adding some minimalist posters to some movies, and some will get removed from a collection after I change the poster (and save).
