Thoughts....
I am having trouble with the eggs in my vertical incubator. It is running the same temp and pretty much the same humidity as my horizontal turner incubator. I am using egg cartons with the sides cut down and bottoms cut out of each cup and turning them by hand 3 times a day (most days). This allows for me to let the new ones rest (staggered hatching) for up to a week while letting the others turn. I was using cardboard cartons, but occasionally they would absorb water from the trough below (wouldn't affect humidity much, but I got wondering about mold or bacteria growing on the cardboard), so I switched to the styrofoam. These are all shipped eggs. Most arrive with saddled air cells, extremely large air cells, or completely detached rolling air cells. (I put the ones with the better air cells in my horizontal turner incubator). I just candled 11 eggs that should be on day 14....and 3 were clear (darker Welsummer eggs) and 10 were quitters (looked about day 10. I did remove 1 egg a week ago that was starting to smell (incubator had a slight smell to it) - this is also when I switched out the egg cartons. Do you think that these eggs may have picked up something from the cardboard cartons to make them all quit like that or do you think that it is just damage to the embryo due to rough shipping hat caused them to quit? I had really good luck using the cardboard egg cartons the same way in my much smaller Janoel incubator...so just kind of stumped at the moment. I also candled my 4 day old Araucana eggs (air cells were on the better side) that are also in that incubator and I have 5 out of 7 viable eggs. I just removed the eggs temporarily and went and washed incubator just in case something is lurking in there.
It's really hard to say when dealing with shipped eggs. I received two shipments of hatching eggs from the same exact breeder, same flocks, but one week apart. The first batch had 50% viability and the second batch had 100% viability. Both had some visible damage from shipping, while the 1st batch definitely looked worse, but to me that also shows just how much of a toss up shipped hatching eggs are because I can't imagine circumstances for that particular flock changed all that much in one week.