Eggs Too Thick to Hatch!

Has anyone ever had a duck that lays eggs too thick too hatch because they can't dehydrate properly? I don't think until now I have ever noticed this before, but we generally hatch so many eggs at one time that I maybe just haven't noticed before. I am keeping one of my favorite new pairs of Aussie Spots down at my house in town this year though and one has been laying incredibly thick eggs. What is really frustrating is that she has been very prolific (laid probably 90-100 eggs and almost all fertile).

I am running 5 incubators this year and have one running dry just for this bird and a few other eggs here and there. I started misting the eggs once, then twice a day and began having better luck with her eggs. I have three weeks worth of her eggs in now that I started washing extremely well (which always results in eggs that dehydrate more) in addition to spraying twice a day. These seem to be on track more than the first several hatches. It is so bizarre though (and she is my only hen out of several dozen doing this). The initial eggs didn't dehydrate hardly at all and were so dense it was actually difficult to even crack them! They are hard as rocks!