Sion's Iceborn Gauntlet

I was just in an ARAM with Sion and bought Iceborn Gauntlet as a second item. But throughout the entire game, it didn't proc once, I could see it go on cooldown for half a second when i hit someone with a basic after having used an ability but the zone and slow effect never occured. We ended up winning the game nonetheless so this is far from a whiny sore loser's excuse for a bad game I just think it's good to point out little glitches for the developpers to look into.