Sion Q and R is disabled/not working

This happened to me 2 times while I was playing in Summoner's Rift (Beta) and playing ARAM

To be more specific, this bug had happened before patch 4.21, and it still exists after.

I lost a game because of this bug in Summoner's Rift Beta (before patch 4.21), but not, the game in ARAM (after patch 4.21)

I really like playing Sion in the jungle and just playing him in-general, but if I can't use 2 of Sion's important abilities, all I can do is just stand in the middle of a fight or just have a really slow wave clear.

What causes the bug is beyond my knowledge, but as far as I can remember, both games had a champion with hard cc abilities (stun & fear) and might have hit me with said hard cc before I had finished channeling q. Another possibility, I was quickly tapping q when I'm in the middle of fights or starting a fight after Q was finished channeling and was on cool down.