Volibear chosen of the storm not proccing until dead

Every game that I've played as Volibear in the last month has had Chosen of the Storm 9/10 times not proccing until death. I could sit there with 3 health bars and it won't go off... I was hoping that this was a known issue and would be fixed by this patch, however no luck. So consider this my formal bug report... Chosen of the Storm is either not activating quick enough at the 30% mark, or it's just not working at all until death. Take your pick. :( After death, my CotS has just started it's cooldown, so I know it's activating, but maybe it's just not doing anything. Lol.