Unfortunately, this doesn't seem to work either. It seems that a Playlist cannot be set to the Seek action, only the Music Segment can. I have tried two events, both setting the Seek to 90%:
-1.Play->Playlist, 2.Seek->Music Segment. Here, the Seek doesn't work, the track starts at the beginning.
-1.Play->Music Segment, 2.Seek->Music Segment. Here, the Seek works correctly, but the track does not loop because the event isn't called at the playlist level (where the loop takes place).