Good morning, this is very strange. I have been using Luigi for 6 months and it has never happened to me. The Napoletana cooks it perfectly in 2 minutes top and bottom.
What programme do you use for cooking?
What type of dough do you use?
Let me know.

Do you still have semola or even flour on the stone for the first pizza? If it works with the other pizzas, it's probably not the oven. I don't have this phenomenon.