iTunes Album Artwork Incorrect or Missing

I recently revamped my computer and am in the middle of putting back my music library into iTunes. I try to import some purchased albums and when I load it via either the CD or add the mp3s manually, either the artwork “cannot be found” when I go to add it manually or the album art that appears is from the same artist but from a previous album.

Some other albums I find are in the iTunes store, but go under a different name like “Reign in Blood (Expanded Edition)” instead of simply “Reign in Blood” or “White Pony (20th Anniversary Edition)” with that version being the key to having artwork show up.

Do I need to change the info on the file itself or rename the album on iTunes in order for the album artwork to link properly? This is thoroughly confusing and shouldn’t be an issue, but I keep seeing people having similar problems and hope someone has a fix that I can use to solve it.