The problem is that some broken playlists may be there on the disc but may never be used by the disc's user interface. In such a situation you wouldn't see the problem when playing the disc with an "official" player which shows the full user interface and let's the user decide through the interface which playlist to play. Maybe something like that is what has happened here. Or maybe (as you say) it's some kind of interactivity stuff. Anyway, I'm glad to hear that eac3to is innocent. One bug less to fix for me...
