Summoner spells randomly won't cast. (Video link)

Summoner spells are simply not casting, randomly and frequently. I reverted to default binds, I caught it on stream multiple times, singled out a video.

You can plainly hear the keyclicks registering, as the game makes a sound when I push the button, but the spell is not casting. This only started happening after the recent patch. I can't replicate the sound that the keyclick makes in game when the spell doesn't cast, which is different from both the on-cd and cast spell sounds.

Highlight link:

http://www.twitch. tv/kfrr/v/14849092

(remove the space between the '. tv')