{Gameplay} Volibear's W

i have played tons of games on the bear, i'm mastery level 5 and i know what i'm talking about. yet it seems that volibear's w only sometimes halves the cool down when you bite a monster, it seems that if you lag it sometimes just doesn't reduce it and that is a major problem for volibear junglers. it has been a problem for a few patches even since mid-late season 5 to now which is patch 6.4 soon to be patch 6.5. although i have no filmed proof i still would appreciate if someone looked into it. Please and thank you.