Yellow Shafted Flicker update and broken egg and embryo

Curiouser and curiouser...Drew found a broken bird egg with embryo parts scattered on our back deck. The Yellow Shafted Flickers moved their nest to a different location on May 22nd (18 days ago.) But, ever since then we have heard them and seen them going in and out of this nest hole as well, but figured they were just using it as a roost if the original eggs in their other nest did not hatch out? And, how did this egg get smashed? There are bits of yolk and embryonic fluid strewn around as well. Did a predator go into the nest and drop the egg, or were the woodpeckers moving their nest to here? Strange...

Looking at the developmental details that I can see on this embryo, I can only assume that it is around a 10 day old embryo of one of the Yellow Shafted Flicker eggs? Here you see the tail (ventral or belly side of the bird) and thighs.

I am at a loss. Did the woodpeckers move back in and have a second clutch of eggs? Here is the ventral side of the beak. This is confusing to me as I thought that the indentation was a nostril. But...

Here is the dorsal side (top) of the head with beak. I don't see nostril development yet.

Here is another view.