Working my way through Cultlands,eliminating groups one-by-one. Three groups left: northernmost (Tank & Hunter, Pyro already killed) / Brother Lundgren & Hunter (butcher killed) / Southwestern group (Tank & Hunter). Now I killed the SW-group and left to the Ark for upgrades. When I came back, the Hunter near Brother Lundgren has disappeared and is nowhere to be found, no body, no loot. The N-group is still intact.
This happened in my previous playthrough as well.