Sion Q Cancel Bug

I have had this happen so many times, I charge up my Q after sidestepping and dodging, and my right click seems to cancel my Q charge when it's not supposed to. This has cost me so many lanes, and sometimes even games when I could've lined up a whole 5 man knockup, but instead all I get is a free reduction of mana and my Q going to cooldown for absolutely nothing.

Rito, pls fix