I think I'm having similar issues. I think the humidity was too high at hatch, sometimes over 80%. I had to assist 4 today and of those 3 are in sick Bay. They needed cleaning up since the inside membrane was stuck like glue in the areas that were exposed to air. I'll give a better recap tomorrow as I need to go to bed- very long day here. Goodnight...
We have or fair share of rain it has been a very wet winter and spring . I run completely dry and the humidity stays 28% to 35 % there is a lot of close to the surface underground water here and relative humidity is on the average 65%.I live at the head of a valley where the river forms .prevailing winds are from the northwest and that is also the way the river runs . I am sure to high incubation heat is the biggest problem I now have. but it could possibly be hatching heat as well .I say this because of the large fluid content of the eggs at the end of incubation at lockdown also I had pips on the eighteenth day when I went to lock down

High heat they hatch early. These are not small eggs and some are sticky so much so I had to wash them after the assist . only the assisted chicks were sticky others hatched fine. Some were stuck and died at the pip site .I'll see if the lower temperature increases hatch rate .next hatch week after next and it's a bunch .