[GAMEPLAY] Sejuani W activates on hotbar, but no animation/damage is applied

I was casting my W, and the skill went immediately on CD, no option to toggle the activation of the AoE. No damage was being applied at all, and no animation was going off. But the skill would go on CD and the mana was being spent.

This is the first time I've noticed the bug, have not tried to reproduce yet.

Happened in the last few minutes of this game: http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2198613436/38005667?tab=overview