I am playing the beta on Xbox One and in a few lobbies of 08 level dark zone I was being attacked by invisible players with silent sniper rifles or silent assault rifles. It seemed that they were either A. shooting through walls. or B. Literally invisible and killing everyone. Those players were also able to steal my loot from afar. I've included a link to one situation of me being killed by a ghost player. My loot was taken by my partner in this clip and not by the cheater.
I didn't find the right solution from the Internet.