I don't know either, could be an issue with the eggs being dirty or something but I would tend to lean more towards a temperature problem, if the eggs aren't developed fully then it isn't likely a high humidity issue, usually with high humidity the chick grows fully then drowns when it pips internally or it grows too large to position itself to pip, it sounds to me like your eggs died before they were fully developed. Do you have a trustworthy thermometer and hygrometer? That would be my first suspicion is that the temp wasn't good, what kind of incubator is it a still air or a fan type? Still air models are notorious for having varying temps throughout the bator whereas fan models circulate the air and make it more uniform though not always perfect either. Also if you are using a incubator with a high capacity like a little giant or farm innovators model that can accept 42 eggs in the turner you will want to add plenty of thermal mass to the unit especially if you are only incubating a small amount of eggs, these machines run best when filled to capacity so if doing a small batch lay some jars of water or baggies full of water or whatever you can in there with the eggs, fill it full of nice clean rocks if you have to but you need something in there besides the small number of eggs to absorb heat, if you have that it will regulate the heat much better. I even ad plenty of thermal mass to mine when I run a full load of eggs and I never have a worry of the temperature.
