[Game Play] Kayle healing incorrectly

While playing a game of ARAM, i was using Kayle and building AP, I maxed out my heal and got a few AP items, making the heal of the ability be over 300, however, when healing teammates, it only healed for 165, despite having more AP later on, it still continued to heal for the same amount. Clearly something's wrong here, and it's not my math. Also note this still confused when the skill was capped, and the capped skill heals for 240.