Dead chicks with partially unabsorved yolk

[Segenam]

Hello,
Firstly, English is not my native language, so sorry for the bad writing
Around %30 of my chicks doesn't hatch, even if i wait 2-3 more days after day 21. As you can see in the photos the yolk isn't fully absorved. I calibrated my digital control termometer according to old mercury style termometer. I keep eggs at 37.7 C ( 99.86 F) and %55 humidity for 18 days and %70 after that. I don't think the problem is about temparature because unhatched eggs are not grouped at the same edge or middle of th box. This was my 3th hatch but still couldn't able to figure it out. Need help.


Looks like they died around day 19-20
https://comal.agrilife.org/files/2019/12/Chick-Embry-Development-1024x685.jpg

 

[Kiki]

Humidity is too high.
Next time try lowering it down to 30% and only raise it to 50% on hatch day.

 

[Segenam]

A few people mentioned it as well. Wherever i read almost all resources say %50-55 humidity. I live by sea side, so humidity is normally high as well.