I do not know who will relate to this, but I have logged 15 hours into this game so far, and the melee messed me up so many times.
I would see my target.
I would strike my target.
My target would disappear.
My target kills me from…behind?
I have no idea what the lunge is doing to the spatial location of my character, but it is really messing up my awareness. There is of course the melee —> gun swap —> melee exploit, but honestly this problem is worse.