Dang, that really should keep them from splitting. Even heat and escape holes normally do the trick.
And they usually have instructions where the temp is the same as most pizzas, so it can’t be heating up too fast for the escape holes to vent (which shouldn’t even be possible at oven temps at all, but it isn’t impossible I guess).
Only other thing I can think of is that any surface ice could make the coating cook unevenly, leading to a split where it starts out colder and stays wetter. But that’s difficult to fix if that’s what it is. But I’ve seen it happen on breaded items before.