It might sound like a gross proposition, but it really isn't that bad unless you have a really weak stomach. I open mine up sometimes to see where they stopped. Did any of them even get to the sir cell? Sometimes if they have vaulted skulls, that can make hatching more difficult (at least that's the reason I was given when I started hatching)... Sorry for your loss
I did open them up one stop around the 10 day mark and the other 3 look as if they stopped around lock down. They had just started to absorb the yolk sack. You no there heads where vaulted.. I just wonder what happen????? I SO WANTED some polish babies..
I had an experience like this recently with my own white rock banam eggs. No pips, two had stopped around day 15 (or a bit later) and four had died during lockdown. They had pipped internally, but never pipped the shell. I never found out why mine never hatched. It might have something to do with hatchability, and wether te breeder often hes ut her chicks. The breeder I got mine from tells me now that she often has to help chicks out, so it might be allowing less vigorous chicks to reproduce.
It's hard to lose chicks before they get to hatch. Take it as a learning experience.