Enabling this checkbox only after an album has been assigned the “wrong” album artist, won’t help.
If it’s unchecked, the album artist that’s assigned to this album on Musicbrainz.org is used, no matter what is in the embedded meta tags.
To clear that up, you’ll need to enable “Prefer local metadata” first, then perform the Plex Dance “light” with the whole album.
(“light” meaning without step 4)
