Unable to Use Q, R, and B as Katarina

I have gotten to the very end of the game as Katarina and been unable to continue fighting because my Q, R, and B stopped working. I have verified that this is not an issue with my keyboard and have tried both tabbing out and restarting the game to see if that would fix it. Neither were successful. The bug first started after I purchased my 6th item, Guardian Angel. Once the bug presented itself, I decided I'd try selling the GA to see if that fixed it. Both abilities began working again, but stopped after I used my B to get back to base. I tried buying new 6th items and selling them, but could not get the buttons to work again.

When I would use Q, the area would appear like I'd be ready to cast it, and the character would even follow enemies once clicked until she got in range, but once she was she just stopped moving altogether as if the ability had already been cast, but no animation or damage was done. The R and B did the same. The character would stop moving, but nothing would happen.

This bug only seems to happen near the end of the game, particularly after I buy a 6th item, but that may be just a coincidence.

Items in the most recent game: Sorcerer's Shoes (Alacrity), Will of the Ancients, Luden's Echo, Rabadon's Deathcap, Abyssal Scepter, Guardian Angel/Zhonya's Hourglass