Alisters only heals for 25% to his teammates instead of 50%

nothing more to be said his triumphant roar with teammates around will only heal them for 25% of the heal instead of 50%. And sometimes less then 25%. I would triumphant roar with a teammate around with no creeps or enemies i will heal for 180 and they will heal if im lucky at 50 ish. most of the time much less.