Re: Unemerged and ?non-viable brood???
"Bald brood" is not uncommon can be caused by rearranging the frames or pushing them closer together during inspections. It's also probably a symptom of other stress - robbing, weak population, dearth, disease. Worker bees that are too few, otherwise occupied, or too weakened to do a steller job. Address any stress that you can think of.
Don't worry about the bald brood it may be viable anyway, but will clear up when conditions improve overall.
Merry Christmas to all - especially to congress for not kicking us in the knees again.