Sion Q and R stop working, but W and E are functional

While playing a 5v5 as Sion, about 20 minutes in, I noticed my Q and R would not activate, but W and E were fine. Pressing them (Q and R) would make the same noise as if they were on cool down, which they clearly were not. I thought it might fix itself once I died, but that did not work either. This went on until the game ended, and I have not tried to play as Sion since then.