It could have been too humid if it was hot and muggy, I suppose. I have not experienced that with my broodies, so I couldn’t say for sure. The thing about a broody hen is, she was made to hatch eggs well. She has just the right temperature and humidity built in, so the conditions are perfect.
I...
In my experience, any chicks that are going to hatch under a broody will do so within 24 hours of the first one that hatched. Are all of your eggs bantam eggs? They do tend to hatch a bit earlier, so if your remaining eggs are standard sized, they may be a day or two later than the bantams.