There are a couple of things to do to make sure they stay together. To start, spread the filling evenly on the tortilla. Then to roll them, making sure you use both hands and roll tightly. Last, place them seam side down on the baking tray when you freeze them. It also helps to place them in the air fryer basket seam side down for the first round of cooking to keep them held together. Then when you flip them over they are more likely to stay sealed.