Sion's Q and R stop midgame forcing to completely close out of LOL and relaunch the application

So I'm not certain at this time what is causing the issue or approximately when it occurs. I have experienced this occurring twice in the past couple of weeks. Coincidentally, these are the only couple of times I've used Sion recently that I can remember. The first time was during a Summoner's Rift game and the second happened yesterday during an ARAM game. What will happen is when you hit Q, you'll hear the normal "click" noise indicating the ability has been launched, but then nothing happens. Same with his ult. You can imagine how bad this is if you are trying to get away or if you go up to an opponent expecting to initiate his Q to potentially stun them. If I completely exit the program mid-game and relaunch League of Legends and reconnect to the game, it appears to work for the remainder of the game. I would imagine others have experienced this too so maybe someone else can shed some light on what the cause may be. I love the new Sion and want to be able to play him without these issues occurring. Thanks!