On e.g. http://musicbrainz.org/artist/f7133014-2377-427f-a4d4-fc1fea72b82f?va=1
which is the Various Artists display for the artist, the release group display is pretty messed up - there are 4 headers on that page saying "Album + Soundtrack", and 3 saying "Album + Compilation", each with a small random subset of the releases of that type.
It looks like the query used on the various artists release group list page isn't correctly grouping by release group subtypes.