The second objective in the Ajani Pridemate battle appears bugged. I gained a total of 26 life in the battle (4, 9 and 13 life in consecutive turns). The objective properly counted all 26 life in the display, but didn’t give me credit for the objective. I don’t know if the display is counting cumulative damage while the objective is counting only within a given turn.
EDIT: Definitely only counting life gained within a given turn. I was able to gain 15+ life in a turn and the objective gave me the points. Even though the objective showed I had gained more than 15 cumulative life for the match, it stayed red until the turn I gained 15+ life within the turn.
SECOND EDIT: This is also true for the Ajani Strength of the Pride battle.