Egg laying mob doesn't work

the mob i'm making is supposed to lay an egg after it breeds, then after 10 minutes the egg will change to a cracked one, and 30 seconds later it will come out and a baby mob appears, which will later grow up into the adult one. This doesn't work however lol, here's pictures of the procedures, the eggs sometimes come out way too fast and sometimes don't come out at all. Also the babies don't grow up...

none of these work, if you place the egg it doesn't hatch but sometimes it instantly hatches for no reason, the egg won't become cracked and the baby won't grow up... Please help :)