not fully absorbed yolks that are green

I just tried hatching one breed of chicks, and did not have a great hatch. 4 eggs pipped, then nothing for over 24 hours. I decided to see if I could help and found them just about dead with green yolks that were just about fully absorbed, but not quite. What could have caused this?

I would guess that this would be a bacterial issue. Either the eggs were washed in cold water before setting allowing bacteria into the eggs, or there was some sort of bacterial infestation in the incubator at the time of setting/hatching.