That's a tricky one. What are you calling low humidity? Below 30%? Normally, low humidity wouldn't cause a problem until day 18 and beyond... where it would shrink-wrap the chick and not allow it to move into hatching position or be able to pip. What did your air cells look like when you set the eggs? Were the eggs local or were they shipped eggs? Did you candle the eggs when you got them and again on day 7? There are a LOT of factors that can cause embryos to die in the early stages of incubation. Soiled eggs can result in death due to bacterial infection, high temps can kill embryos, old eggs can result in early quitters, and the list goes on and on.
As far as humidity goes, too little humidity results in too much weight loss and will make it difficult for the chick to hatch. Too much humidity results in not enough weight loss and a small air cell... which means the chick will likely drown before it hatches. There is a wealth of knowledge in the INCUBATING w/FRIENDS! thread. The first page has links to nearly anything dealing with incubation and hatching.
https://www.backyardchickens.com/t/...riends-come-hatch-learn-chat-meet-new-friends