Cassiopeias W Bug

I just played a game against a Cassiopeia, and their W was bugged the entire time. I couldn't see it AT ALL. COMPLETELY INVISABLE. So I would just be walking and csing in lane and suddenly, Im slowed poisoned and getting Repeatedly E'ed by Cass and dying. Please remove until this bug is fixed. Sorry I cant give you a screenshot, but f12 is taken up by other-things on mac.