To answer your question
@Gammas Bearded Babies , when I got home last night I candled the eggs that had not pipped yet just to see if they had internally pipped or not. I am very comfortable doing this and can do it very quickly. If I am all at in doubt if they are DIS, I put them back in the incubator and let them be, but sometimes it’s pretty obvious. The one DIS I removed had completely filled out the egg, there was no air cell to speak of. This was a pullet egg, a little bit smaller than the others. I expect the chick was too large and was unable to hatch. Another reason not to hatch pullet eggs, though the second egg from this pullet hatched just fine. Unfortunately I don’t know which one it is because I did not see them hatch! Just saw the eggshell. I mark all my eggs with weights and dates and initial of the hen that laid it, if I know.