That sounds normal. If the embryos pass away, they begin to decay and the blood recedes to the outer ring. The yolk also begins to decay. If you were to leave these eggs in the incubator, there is a chance that they would continue to decay (causing a build up of gases) and explode. Bacteria is often involved.
The yolk of the egg that I opened was still intact so I was able to find the ovum. It appeared to be infertile.
Perhaps I'm crazy... Perhaps the cockerel managed to fertilize this one egg and the embryo passed away and decayed. But I swear I saw the white ovum...