On albums where Jellyfin can’t find images, it always uses the same default image of

[EliteAlien]

I recently moved my library and rescanned. It found a lot of album art correctly. (I use the recommended file structure and naming convention that Jellyfin likes).

But on albums where it can’t find images, Jellyfin always sticks in the same image of composer Ennio Morricone. It even attaches his logo to every single album and artist that doesn’t already have its own logo.

Can someone help me figure out what’s going on? Thanks for your help!

I use Jellyfin for a lot of my music and I can say it's picky. I don't tend to have wrong album art myself to often. Though, I find it's usually down to two things concerning the metadata. How are you getting your metadata for the internal files of your music? It could be that you have bad metadata in the files and/or Jellyfin band/artist page and Jellyfin is reading that and assigning the wrong images to it based on what is thinks is correct.

What I recommend is using MusicBrainz Picard on your music files. If you are fine with a terminal use Beets, but be sure to compare it via the Musicbrainz website to see if it matches up. I've had a few miss matches with Beets. Picard you do everything via the GUI by hand so it's your own fault if you mess it up I guess.

If the metadata in the .flac, .mp3, .ogg, et cetera is good, it still could be the naming in terms of the metadata. I've found that some bands or artist with similar names take over another and the wrong MusicBrainz and such ID's get plugged into the band or artist profile page on Jellyfin. I've had to set the correct information and sort of lock the pages from being taken over via the edit metadata button and clicking the, "Lock this item to prevent future changes" check box and saving.

This likely doesn't apply to this case, though putting it out there. There has been one occasion I even had to rename a few artists folders where the music is stored and potentially change the metadata in the files too so that Jellyfin would properly display an artist. Anything with backslashes, dashes, and some similar named bands can still be taken over just by the fact it has a similar name and the above just didn't work. One example is a band named D/A/D would only show up as D in Jellyfin so I had to rename that and the metadata to something else. I tried D-A-D but Jellyfin kept replacing that with another band. Which ended up making me do it all again to name it D_A_D. 

I know I may have gone a bit far, but I've always found Jellyfin to be so picky with music. It's never been their main focus and a lot of things break it. Though, I hope through all my suggestions of things and playing around with stuff, perhaps you can find the answer.