Also re: lower humidity, I always start dry and weigh my eggs and the tribbles needed hardly any water added at all in spring weather. I would have had a good hatch if it wasn't for what happened to the incubator that one time (the error messages turned out to be high heat alarm and power loss alarm)
I don't know what's up. All I know is they hatched a lot of babies in desert dry conditions.
Let me know if a broody become available.