this is based on studies online. The thick clear jelly-like membrane is caused by temperatures being too high later in incubation. The "remains" of the eggs are thick and copious. In ideal conditions, there is a very thin light pink remnant in the shell.
And her temperature had to have been too low during the beginning of incubation, otherwise they would not have been sooooo late hatching.
High temps is NOT going to cause the thick jelly. If anything LOW temps and high humidity.
Sticky embryos (embryos may be smeared with egg contents) High average incubation humidity Follow recommended incubation humidity. Check size of air cell as an indicator for adjusting humidity condition.
Low incubation temperature
Follow recommended temperature settings.
Three different websites Cant be wrong!