I don't know if this is intended, but the Album Artist field adds the tag as BAND and not ALBUM ARTIST. If you go to extended tags you can see that.
I use foobar2000 and the BAND tag gets recognised as a custom tag (the same as iTunes tags).
I use the album artist tag for VA albums (Columns UI setup with NG Playlist, so it gets messy without the album artist tag for VA albums).