Ive killed a couple bears and from my experience on alot of bear hits the fat from the bear can plug up the entrance and exit wombs. That would explain the lack of blood on the ground. Does not mean that the hit wasn't a good one. Just a possibility. I would look and see if there is any terrain that travels down hill that the bear could have possibly taken. Both my bear kills they traveled down hill. I found the first about 200 yards away and the second one was about 400 yards away. On the second one I hit the front shoulder though. That explains the distance it traveled. I don't know if its legal where you are but a good hound can lead you right to the bear in no time flat. I think with the pass through and aiming center that you have a dead bear somewhere. Don't quit. These suckers have been harder to track than anything else I have shot. I believe its out there waiting on you. Good luck.
Whitey