We were playing on the Stable Branch, using game-client "0.35.115.188".
I just bought my friend the game. It was his first time playing. I have a well-established character with an ammo-box, hunter backpack, two med-kits, and two (damaged) protector cases. I carry a tricked out M4 rifle with a bayonet, and a weapons flash light. All parts are pristine.
He has an M4 rifle. We're both wearing green spray-painted helmets. He also has a hunter backpack and a hoodie. His gun is not in as good condition, but it's not terrible. He has a damaged protector case with a revolver in it.
Consistently, when alone on the same (low ping) server together "DayZ Central 1-2 Hosted by MultiplayGameServers" [ 76.74.253.73:2302 ] -- it is a hard-core server.
We were in and around Berenzino.
I have never had this bug with any of my other friends.
He never saw me rubber-banding or vanishing.
He was able to punch me in the face without his position updating (at my direction to try it), making it impossible to fight back.
The server was not lagging in any way, and items updated quickly on the ground, although we did have some food items disappear when we used cans on them, opening another can would cause that one to vanish, and the old to reappear.
Eatting a can till it vanished also caused other food to reappear.
Weird inventory updates. Don't know if they're all connected or not.