Maybe not a bug but just a warning -
If you upgrade over the top of 2.39h BAND should have replaced ALBUMARTIST, but it does not appear in the field lists for tag panel, extended tags or filter. Instead ALBUMARTIST is still in the lists and maps to a TXXX tag field. There is nothing mapped to TPE2.
You need to uninstall 2.39h to force a rewrite of mp3tag.cfg