I get this all the time, pop smoke screen BOOM I GOT 0 HP but im stil alive? potions gives me no health either, then if i remove my quiver and put it back, WAT? all my hp is back.
its a bug, you dont actually lose health in smokescreen(you are completely damage immune). it just looks like you did. which is annoying as hell because then you dont know how much health your at at and the red flashing screen is in the way. removing and equipping anything with vitality or %life fixess it as it resets your max health. but yes they need to fix this.