[GAMEPLAY BUG] Garen's Q

I got Garen in an ARAM game, and we were at the Nexus. Knowing that his Q is an auto reset, I used my q after my auto. But when I used it, for the whole duration of the Q, I couldn't attack the Nexus. The inhibitor re-spawned and I could normally attack it with my Q, but not the Nexus.