She was doing so well, after abandoning her first clutch and then flinging the sole surviving chick after I incubated them for her. I later discovered the flung chick, as well as the quitters had the ''black spot'' of doom.
Once it finished hatching in the sterile incubator, I checked this baby as well and it appears to have black spot as well, although it doesn't look quite the same as the other one. I'm not sure... I checked on it again this morning and the spot seems to have shrunk, so that's good... I think... Black spot is caused by so many things, but since it wasn't coincidental at least now I can make an educated guess the cause is congenital, which narrows it down to either atoxoplasmosis or a fatal gene.
This baby seems really strong, it's made it through 4 feedings (the parents will incubate but not feed yet so I'm keeping an eye on that little crop) but the black spot has a really high mortality rate, so I'm not holding my breath.

No more nests from this pair, they will all be born with black spot, and their parenting skills worry me anyways.