I am on my first incubation and its now day 22 and I have an egg that is like the picture below. I don't know if its not going to hatch and if not do you people think its died?
You can see in the first picture the dark mass and then cloudy area beside it and of course the air sack in fat end of egg that is clear. At this age the entire lower end would be dark as it should be a fully developed chick by day 21. It died at some point during incubation.
Are they shipped eggs or local? With shipped eggs they can simply quit for no real reason. Transport is hard on them. For local eggs there must be a reason for quitting in second week. Are you turning the eggs? Did you have a heat spike at that time and possibly cook them? There is a reason but without being there every day watching the incubation I couldn't guess what it is.