Collections

[TheDreadPirate]

What I suspect happened is that when you restored and started Jellyfin you did not have your media in place. There is a job that runs when Jellyfin starts that cleans up playlists and collections of media that is no longer present. So if you restored Jellyfin before restoring your media to their original locations, or correcting permissions, Jellyfin would have emptied your collections.

This job can be turned off. Dashboard > Scheduled Tasks > Clean up collections and playlists. Open that job and remove the trigger.

If you have backups of the collection XMLs, you could try restoring those.

For docker
/config/data/collections

For Linux
/var/lib/jellyfin/data/collections

For Windows
C:\ProgramData\Jellyfin\Server\data\collections (I think this is right)