There is a lot I don't understand about the yolk process, but it's been my experience that when the veins are gone and the yolk is still that big that there is something wrong with them.Yes most of the veins had gone, I assumed it was because it had died.
Sometimes you're darned if you do and darned if you don't. The first time I saw the bruises I ignored them, none pipped externally and they all died, so now I pip externally for them when I see a round bruise at the small end or the wrong side and the majority are ready to hatch in 48-72 hours after that. I still do lose some, but not enough for me to change what I do.
! I am excited and nervous for you!