Had this a few times now. Shot someone down with the M4. Cant hide body so he was unconcious, I even checked his pulse with said "strong pulse".
Now to finally kill the player I wanted to shoot him in the head which wasnt possible. The bullet only hits the ground underneath, not his head. I had to shoot in his body, blood spilled out and he "moved" a last time.
Stupid bug cause everything was totally ruined.