Player Attack Move Click not Working Properply

​I have my Player Attack Move Click set to my MB1, and it is bugged and very unresponsive. It either doesn't target anything, targets the wrong thing, or doesn't target anything.

I had my mouse on top of a Vi (literally smack bang on top of her) while i was playing Lucian and was clicking my MB1 to try to attack her, and after all of my spell casts onto the Vi, Lucian continued to attack the Rift Herald that was over in the corner agro'd onto another champion.

I have noticed the input would have to be recognised because when i click it still comes up with the 4 orange arrows animated to point into the ground, but my Champions will still just walk to the spot rather than attacking the closest enemy/Minion, or it targets the wrong minion or champion that is much further away from my mouse than my intended target.