I placed 12 shipped fertile hatching eggs under my broody hen. 9 of the 12 hatched out on days 20-21. Today is day 23, and I removed the 3 remaining unhatched eggs after she abandoned the nest to care for other chicks. 2 appeared infertile, but one lavender orpington egg was a fully developed chick that never pipped. Any ideas on what might have happened? I'm very pleased with the hatch rate but hate losing one that was so close, especially a lavender orpington.