Of the ones I have done........usually overstuffing as well for bursting open.
Ive even rolled them like a date cookie. Very thin and then sprinkled cheeze over most of the flat and rolled it up and pinched them very well, just to watch the cheeze squirt out.
One more thing I will try is to make sure when I probe it w/my polder type thermometer is to not poke it in the center of the fatty.
Im thinking about halfway between the center and the outer edge. Pulled the probe and watched the cheeze just squirt out like crazy.
Im thinking less stuffing of cheese, better pinching of the seam and wrap in in plastic wrap, chill for at least an hour back in the fridge before placing on cooker. Something w/the binding of the cold fat vs. warm fat.
One more thought.......trapped air expands when heated. Try and make sure there are no airpockets in the fatty when sealing it back up.