With my first hatch of button quail (Chinese Blue-Breasted Quail/King Quail/C. chinensis), I had only one chick hatch out of fifteen eggs that I set. At day ten I candled, and found four infertile eggs. On day 16 (hatch day), there was nothing. I chekced the thermostat and the dial had been moved a litle, and the temperature was several degrees lower than it should be. In the end (on day 22), my one baby hatched, with assistance. The next day I opened the other eggs carefully. All were dead. Four were fully developed, but failed to pip. Another was fully developed, and pipped into a blood vessel on the membrane, and either died of blood loss, or drowned, and one was mostly developed, but quit a few days before lockdown. The remaining eggs were only a tiny bit developed (about day four for a chicken egg, so day 2-3 for buttons), and some had been damaged in shipping, and didn't develop at all. I'll be posting pictures of the single chick soon.