[GAMEPLAY] Fizz's Q doesn't apply on-hit effects

I uploaded a replay of my friend trying to ks a kill from me (to share with other friends), but I noticed that my Q did hardly any damage when I have sheen on. https://www.youtube.com/watch?v=xOeTuMBVrFE&feature=youtu.be http://gyazo.com/313b5b18b269ec41f41e9e0080a5380e

Uhm to replicate this simply W-Q a target with sheen. I looked back to this thread - http://forums.na.leagueoflegends.com/board/showthread.php?t=3834665 and it suggested that pressing w nullifies the on-hit effect. The sheen proc was active however after I dashed through her.

Edit 1: The info I said about W-Q seems irrelevant and only Q seems to be the issue here. http://gyazo.com/3e36d30a8235529d0d4fc6b84faa6427 - This screenshot shows that I q'd first and the q didn't proc the sheen. Maybe pressing w after immediately q'ing nullifies the onhit?