It's happened before, but this time was a heartbreaker. Was up a tree at my best stand in the evening and a high tined 10 pointer came out of the heavy brush 40 yards away headed straight toward me at a walk. He was my 39th buck sighting this year, and the biggest I'd seen to this point. At 26-27 yards he made a left turn putting him broadside. I raised my crossbow, put the crosshairs in tight against his front leg, and shot. He continued walking kind of hunched over as he walked, and I raised my binos and could see the entrance wound a few inches behind his front leg and up about 6 inches from the bottom of his chest. I'm waiting for him to keel over, but he continues walking and lays down about 90 yards away where I could barely see him. I walked out and waited a half hour, thinking he would be dead by then. When I go back he gets up and walks away into the heavy brush. WTF? The next morning a buddy and I went back and there was almost no blood anywhere from where he's been shot, laid down, and then walked into the brush and beyond. I found my bolt yesterday sticking in the ground at a left angle from the line of flight after it exited the deer. The bolt had been deflected upon entering the deer and didn't get enough of it's lungs to kill it quickly when it went leftwards through the deer. I'd had it happen once before when I shot a doe for meat. The doe had done the same thing, walk away and lay down within sight. I had hit the doe exactly where I wanted, and when I went toward the deer it got up and fast walked away, resulting in a long trailing of over 400 yards in heavy brush, aided by the dog I had at the time. As my rottweiler went along with us when he'd stop with his nose to the ground in front of us we'd go there and there'd be a drop of blood. The deer was still alive when we got to it, but couldn't walk at that point. The bolt had exited the far rear leg, after a seemingly perfect broadside shot, breaking the leg bone completely, and the doe still made it over 400 yards on 3 legs.
TLDR Hit a big buck and didn't recover it due to bolt deflection upon impact