I’ve had one bad hatch in mine, setting was 100 F and actual temps in egg slots were 98.8-100.9 F so an average close to the ideal 99.5 F. The two that hatched did so at the beginning of Day 20, plus eggtopsy on day 21 showed dead a chicks in beak over wing malposition, which can be a sign of heat stress. So, I think my temps were too high, even though some slots (nest air intake, I think) have temps quite low. I’m wondering if having the incubator full would even out those hot /cold spots..Lowered the temperature 1 degree. I ran it at 98 instead of 99... likely a calibration issue. I also stopped making mistakes like opening to remove a few chicks to stop them from kicking around hatching eggs. Turns out they do fine rolling around but they do not do so fine when they are shrink wrapped. I also kept the humidity very low before lockdown, let it run dry the first 3 days, put in a little water , let it run dry and wait 3 days before filling it. Then when they hatch I add a soaking wet sponge as well as filling all water chambers. That may or may not work for you. I hear other people doing completely different things with their hovabator and having more success than I do.