If you trigger the MIDI timing clock to be sent, it will never stop being sent until you trigger a MIDI message in MobileSheetsPro to stop it. So if you have one song that sends the message, you use a MIDI action to trigger the sending, or you use a smart button to trigger the sending, it will keep being sent as you switch songs. If there is a MIDI command you can send to MobileSheets to start triggering the timing clock, that might work well, so set up a MIDI action for that if so.
Mike
Mike