I have no clue if this works with Apple Music enabled, but I encountered this bug before, and I fixed it like this:
* select all tracks on the album
* right click -> Get Info -> Artwork
* click on the existing artwork and press Delete (you may to have this more than once if another wrong artwork appears in its place)
* drag the file with your correct cover to the [now empty] Artwork section
* click OK
* iTunes may ask you "do you want to make changes to multiple items?", click OK.
* select all tracks on the album
* right click -> Get Info -> Artwork
* click on the existing artwork and press Delete (you may to have this more than once if another wrong artwork appears in its place)
* drag the file with your correct cover to the [now empty] Artwork section
* click OK
* iTunes may ask you "do you want to make changes to multiple items?", click OK.