I had several sizzles and blue jersey giant eggs incubating this past month. I have two hovabators with auto turners, fans and thermo/ hydrometers. I always keep the temperature between 99 and 101 and the humidity above 50%. On day 14 I candled the eggs and tossed the ones with no development. Come the 20th day several sizzles hatched. Another few hatched on the 21st day and then NOTHING. I let the incubator sit, maintaining the heat and humidity, for a few extra days with 0 results. On the 26th day I stopped. When I removed the eggs out of sheer curiosity I candled and then cracked them open. Low and behold I had fully developed and feathered chicks inside, they just didn't hatch. My question is what did I do wrong? I kept the heat around 99.5 and the humidity after lock down never dropped below 60% but did spike to 80% on a few occasions. Was that too dry or too wet? I had one chick that piped but never fully hatched itself out so after I removed the first hatchlings(48 hrs later) I helped him out and the membrane in his shell seemed tough and leathery. I have a feeling I either had too much or not enough humidity at one point or another. This is only my second time trying to hatch from this incubator and I had one chick develop and not hatch on the first try. Im just curious because my other incubator is due to have a hatch Friday and I have some very expensive birds in there. I want to correct what I am doing wrong so this doesn't happen again. Thanks for all your input. Happy Holidays!