Singed's Q turns off whenever it wants to

[GAMEPLAY] (sorry I forgot to put that in the title and now it seems it's too late)

Sometimes it's just the swirly indicator that turns off, sometimes the ability actually turns off. I'm not sure how, I just played a game though where several times I would be in a teamfight or running from someone and I realize my q had been off for probably most of the fight. Very irritating, please look into it :(