I have a convections oven with a side fan, these ones were baked at 300 and I have another baking at 275 doing the same thing!!! HELP!
I use all kinds of pans in our commercial convection oven - aluminum sheet pans, non-stick pans, Nordic Ware impressed pans. I don't really think that is your problem. As the cupcakes start to get a delicate crown, the fan is blowing that delicate batter and it bakes into that shape. You can try aluminum pans, but I think the real problem is your fan. Maybe you can construct an aluminum foil to tent to try over a batch, and see what happens.