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

That blows.

Are your bolts too light maybe?

A super lightweight bolt would definitely be more likely to deflect. I use the bolts that came from the manufacturer of my Scorpyd crossbow. They're not a lightweight bolt. I've wondered if the deployable broad heads could cause it. It seems like if one or two of the three blades spring back into the cutting position a millisecond before the others hit a rib bone it would be more likely to deflect than a head with fixed blades. Most bowhunters are using them for the field point accuracy and consistency, but the occasional deflection may be a downside of their use, I don't know.

Why didn't you track that buck that night?

I didn't track him that night because I could see no downside to waiting until the morning. I'd also have help in the morning, daylight to possibly spot some sign, blood, or the deer itself that I might miss in the dark. Given that he was able to walk just before dark there would have been the possibility that he would stay alive and be able to move well into the night.

Hunched up sounds like Liver/guts, as does the laying down quickly after the shot.

If they lay down, and don't die within a fairly quick time frame, you need to wait at the very least 4 hours before attempting to recover.  I prefer to leave them 6 if there's no impending weather to wash the blood trail away, no coyotes in the area, or other factors that would make me go in at 4 hours.  Pushing an injured deer is almost the worst thing you can do to your recovery percentage.

I don't know why you would be getting such crazy deflection, especially with a crossbow.  Are you sure you're just not recognizing that the deer is quartered to you in the moment?  Arrows will deflect, but they very rarely will take a hard right or left turn.  I've never seen a completely broadside arrow deflect enough to only hit a single lung.

When you gutted the doe this happened with, what did you hit? 1 lung, liver, guts?  That would be my guess if she went that far.  I can see a leg bone maybe causing that much deflection, but I've never seen it happen even with upright bows breaking the front leg bone.

Sucks that this  happened.  But if they don't go down in sight and die within seconds of the shot, I always give them at least an hour, more likely two.  If I'm not confident I made a good hit, or I see them lay down or slow down and walk before going out of sight, always 4 hours minimum.

Liver shot deer can live 4-6 hours.  Stomach shot deer can live a couple days.  Deer can live on 1 lung for a good long while too.

Tried to reply to your post, too much text for it to show. Good info on different recovery times depending on behavior and different types of hits, thanks. It had been 8-10 years since the doe deflection. The doe and the buck's behavior were the same. They both walked off and laid down within sight. The doe was a close standing broadside shot and the bolt hit exactly where I aimed, center of lungs. The buck was hit probably 2" below perfect. Both were not visible enough that I could tell if they were alive or not. Both walked off when I approached them. Hope it never happens again, but if it does I'll damn sure not make the same mistake of going after them too quickly if they exhibit the same behavior.