3 of mine that didn't make it had vaulted skulls too.
I don't even think 2 of them internally pipped. 2 more were peeping, so they internally pipped and didn't externally pip. 2 more looked like they stopped developing a couple of days ago, so out of the 7, there were 4 that were alive this morning, and didn't make it, 2 died several days ago, and 1 hatched. I'm so glad that I at least got 1.
Oh wow, it is a good thing you helped that one.