This happened to me a few times ever since I started with DayZ SA.
It seems like your character sometimes stays on single spot in server-side.
Yesterday, for example, I died because my body was standing still in some barracks while I was actually somewhere far away. I could see the guy who killed me clipping through walls doing the animation as if he had just spawned (switching weapons). I think this might be a big issue with the network.
I've had that happen multiple times.