I check the humidity day 18 and only add water if required, also keep shut till all hatched, no matter how tempting it is to open it.
I think a few lads are having problems just now. Got some due nxt Sunday. 9 out of 10 fertile and forming well, but a lot can happen in a week. The last few days are crucial for a good hatch rate, so let's see.
Got a broody sitting also, that's by far the best, but not always possible for early youngsters.
Atb