When an animal like wolf or bear are slayn on or near a road, then you cannot select it to get picked up by a hunter.
If your are lucky, then one of the legs sticks out wide enough, but i had it plenty of times, that i had to delete the road.
When the hunter kills it, or is told to do so and is close enough, even when a villager kills and animal, he picks the corpse up by itself. So to reproduce: Don’t have a hunter near, let villagers kill it.