Ok, so I figured out what was wrong with the above mission and the patrol.
I was using this in the last WP for the unit and it was crashing DCS.
mist.ground.patrol('tg1', 'doubleBack', 'On Road', 15)Found my notes form a year ago and started using this in the last WP for the unit and it works.
mist.ground.patrol('myGroupName', 'doubleBack')You can put it in a trigger activated when group enters the zone or put it in groups last WP.