I had trouble finding Crabbe myself, because I'd forgotten where he was.
He's actually just inside the little cave at the very top of the path leading into broken valley where the campfire is (just head upwards/back to broken valley from the first Orobas waypoint shrine until you get to the campfire).
The problem is that his clothing blends into the textures of the cave, and there's some overhanging vegetation that hides the glowing question mark over his head - I walked/flew past several times before I realised/remembered he was there.
Hopefully you just missed him like I did, but if he's genuinely not there, you'll have to contact Larian support - worst case you'll have to send them your save file for them to analyse and fix. Larian is great at dealing with these kind of issues, so don't be afraid to ask.