collection

[5-0]

Are your media files stored on a network share?  There is a job that runs on startup that cleans up playlists and collections when the associated media is not available.  You can try disabling this job.

Dashboard > Scheduled Tasks > Cleanup playlists and collections

Then delete the startup trigger.

I seem to have a similar issue. New to jellyfin i have added videos to a few collections about twice now and after a little bit of time they are all empty. I have them stored on an external hard drive. I havent tried deleting the cleanup playlists and collections task as i didnt want to do something and mess things up more.