thinhorn try moving the bottom connection that holds the butt toward the buckle of the hip belt. You need to tuck that under one of the straps on the side of the belt and then if it is still trying to roll, pitch the toe of the butt out away from your leg when you place it in the bottom cradle.
Mine only ever wanted to roll on my EXO because I didn't have a good way to hold that bottom cradle forward and the top connection was just to a compression strap and not around a stay. Every once in awhile with a heavy scoped rifle if it gets too vertical it might try to roll but those adjustments above will help a ton or eliminate it.