I can not make my users wait any more. So from a result, I tried other way for the loop.
1. Remove the properties for MusicTrackLoopInfo from all MusicTracks.
2. Add new MusicTrack for looping marker. (hereafter called "MarkerTrack")
3. Add new note message which it has only turning point marker. (ex: case musical measure 4/4, Mark a turning point in beat 5th.)
4. Set MarkerTrack as userEvent by MusicTrackNewMIDINoteEvent.
5. Set callback by MusicSequenceSetUserCallback.
6. You will be able to catch event your turning point. So, move the current playing position to 0.0 by using MusicPlayer/MusicPlayerSetTime!! (Set from the main thread !!)
It seems working fine.
I adopted to use this solution for my app BAR1 until Apple will fix this terrible problem. I hope to remove their codes from my source code, soon.
I hope this helps you.