Problems with wind shear in mists and stonevault

Hi all, i play enh and i am experiencing something very strange and haven’t seen anything anywhere and was wondering if y’all have experienced the same. It only happens in the above dungeons where on the staghorns (and other mobs in stonevault that throw a spell then follow with a heal) that if i wind shear the shell, i cannot kick the heal. like i can, it goes on cooldown but the heal doesn’t get kicked. and the staghorn continues to cast. am i interrupting too early? could it be my settings? ui or game? is it lag? in any of these cases, i don’t know where to start looking. if anyone has had this issue, please tell me how you solved it. ty.