To reproduce: 1. Go to http://musicbrainz.org/release/0d70404b-382b-450e-a8a5-678d8a35bbb6/edit 2. Change release artist (moving featured artist to artist credit) 3. Click to tracklist tab: tracklist no appears has 1 and 2 instead of A and B.
Issues exists on beta.mb.org too.
http://codereview.musicbrainz.org/r/2283/
http://codereview.musicbrainz.org/r/2283/