MY fix was something I've never done before, and I've used MP3Tag for . . . twenty years?
I used it to remove all tags from the entire album. Then I recreated tags from filenames. Whatever was hidden in the metadata that I could not see was erased, and now everything sees the entire album as being by the Commodores. No more various artists nonsense.
Only speculating what could have been the issue for 0LD3_DUDE from my own experience.
I had a similar issue with some albums showing up as Various Artists in Plexamp. The Artist & AlbumArtist tags were setup correctly. I discovered these particular files also had a tag called Album Artist (has a space between the two words) that either had Various Artists or something different to the AlbumArtist tag. Example:
AlbumArtist: Accept
Album Artist: Acccept
Any discrepancy between the 2 fields would cause Various Artists to be shown in the Plexamp.