Apple TV ungroups songs in an album
Same here. I found a easy 2 step approach to solve the problem.

1.) Make sure you have ticked the compilation box in iTunes and delete the album artists completely.

2.) After your Apple TV updated the music library the compilation will be together as one (with "Verschiedene Interpreten" in German, wich is "Various Artists" in English). After that you can re-enter any Album Artist you want, the ATV will not split up the Album again.