I’m not sure why, but twice now, I’ve had a Maliwan enemy that was unkillable. He had zero health, but could not be killed. The first time I was able to just run past him after everything else was dead. This was in the first Maliwan area.
The second time, it was after the Valkyrie and the door was past that first part wasn’t opening because “an enemy was still alive”. I finally managed to plant enough stickies to blast him off the ledge.