[GAMEPLAY] Item(s)/masteries dont give proper amount of AP

Today I played a normal game as Viktor and I noticed that with final build (Lucidity boots, Death cap, Void staff, Lich bane, Zhonya, Perfect hexcore + Elixir) at level 18 I had 902 AP including dragon buff (1st). It is weird because I played many custom games with Viktor with the same build and reached 917 AP (same runes, masteries ofc) before patch 5.5. I checked it in custom against bots and still reached only 902 AP.