I was messing around with some game filters on NVIDIA Freestyle on Local Coop (Specifically the DOF feature as you can see on the M4 in the GIF) while I was clearing a building I encountered 2 guys looking over the roof and killed them both and looked in the opposite direction to fight off the guys coming behind me and a 3rd guy appeared behind me almost as soon as I looked away and killed me.
My first assumption was that he may have simply hid behind the AC unit and Sprinted at me, but I hadnt heard any footstep going through my headset.
God forbid, It's an invisible AI that managed to slip through Update 1.4, performed an action that reversed the bug and killed me.
He somehow spawned or Teleported behind me.
Let me know what you think after watching it yourself