Kogmaws passive is BROKEN !!!

was playing a game as kog nearly got kills of 2 enemys atking me but they got me 1st , they where left with enough hp passive blast would kill them both but it did no dmg ....... it did this type of thing several times..

then just now in aram our kogs passive would of got kills but instead it did 0 dmg both me and him both state "wth no dmg !!!"