I am not really a user of the CD-ripping feature of MusicBee, but this does surprise me a bit.
I am guessing most providers will provide an album artist for all their releases, also for the ones that have more than one artist on them.
If that's not the case here, to me it would make sense if in these cases MB would write something like Various Artists for the album artist.
Others using this feature and having an opinion on this could probably create a wish for it.
Or instead of moving this post from Bugs to Questions, maybe move it to Wishlist?