Azir W bug on towers (no cooldown)

Azir's W if used on a tower has no cooldown and can be double tapped on a tower for instant 2x damage, i havent seen anything in the patch notes about this being a thing (but i could have missed it) so I'm assuming its a bug.

i can provide images/video if requested :)

Azir is my main and favourite champion in every way, i love playing him but if i beat my opponent i want to do it because of my actions (and Azir's) rather than exploiting a bug.