Azir passive bug

Hi everyone, I played a lot of Azir recently and I noticed a bug with his passive. When I put my passive on e.g. Mid T-1 and the turret then gets destroyed, there still is that symbol on the ruin of exactly that Turret, although the passove was on cooldown. It's not a gamechanging bug but still a little bit confusing.

Cheers and may your potential be limitless.