If you look at this release you will see that the feat. artists are part of the artist credits.
When I use the green tagger button to load the album into Picard the feat. artists appeas as part of the song name and are not in the artists credits.
Looking at the edit history for this release you can see that the feat. artists were moved from the track titles to the artists credits in 2012 already.
Does anyone have any idea why this is happening?