I have been hatching eggs with my incubator . After several hatch I have other birds die befor always out of the shell . Seems like they are the inside of the egg is very dry and they get stuck .
It sounds like your humidity was off, but I can't say for sure without knowing your exact settings. This article breaks down causes of hatch failures and may help you some:
What is weird is half the eggs hatched fine and the other half died in the shells.they were doing good when we went to bed . Woke up with dead babies. And about 10 eggs had dead bird that died before they started to hatch