Unable to use abilities

Occasionally (seemingly at random) when I load into a match I am unable to use my abilities by hitting my keys, and am only able to use them by clicking them. This bug persists until I completely leave the game and close the client and load back in. Sometimes it doesn't even work the first time I do this. Obviously this can be a problem in ranked games and lead to me getting behind, or a remake can occur while I'm attempting to load back in leading to AFK punishments.