Sejuani "w" not working [GAMEPLAY]

It was really late in the game. I was full build and had a potion on. When i went to go clear superminions I realized that my "w" skill was no longer working. When I tried to use it, it would go on a 5 second cooldown instantly, and there was no animation for it at all. Usually her flail lights up and the next auto does increased damage and then we get that swirling ice storm. None of that was occuring. I thought maybe the animation was just bugged and that the damage was still there, but that wasn't the case. It wasn't doing any damage, and there was no animation. All that would happen when I pressed my w is that the skill would go on a 5 second cooldown. I tried to go back to the pad, fight creeps, fight heroes, and I even died, but the issue wasn't fixed. That's a huge disadvantage to be down a skill. We ended up winning the game anyway, thanks to some crazy play from my friend on trundle, but this is a very serious bug that could cause players to unjustly lose games. I will not be playing Sejuani until this bug is fixed.