Volibear's Frenzy

When ever im jging as voli and i bite a monster with voli's W i don't get the 50% cooldown reduction most off the time it only gives it to me when it wants to but i barley get it if u want to try it out all u have to d is just jg as voli and i can garente you that most of the time or half of the time u wont get the cooldown reduction. this makes it hard to clear camp and stay healthy to gank lanes and i don't see my self using voli in any games in the future until this is fixed.