Does anyone know what happened? I am incubating for a friend and this happened to two of her eggs. this has never happened to my eggs. I recently bought a sportsmans and have had 100% hatch rate until now.
How developed is the chick? Am I right in understanding that your eggs were in the same incubator and hatched without this issue?
My guess is, given it happened to her eggs and not yours, this is a lethal gene issue. Generally, its unused yolk that should have gone to provide nutrient to the developing embryo.
Is it super sticky? I've had this problem with some eggs lately, super sticky thick gelatinous ick that stops the chicks from zipping. Some of the eggs I've found this in have had thinner shells than others. I think it may be due to a significant temperature spike during incubation or some kind of humidity thing. It may be what's left of the albumin when it loses the water content. My answer is: I don't know.