[Gameplay] Varus's Piercing Arrow not working.

During my last game as Varus , Varus's Piercing arrow would not go off. I pressed my mapped button. Didn't go off. I pressed my other abilities mapped buttons. They went off. I clicked it manually. Didn't go off. I clicked my other abilities manually. They went off.

All my abilities are not on smartcast. But once I turned it on, it started to work again. I turned smartcast off, and Piercing arrow started to work again.

Please take a look at it. I was also wearing the Heart Seeker Skin, Maybe that has something to do with it?