Unreal engine bug report for the issue with using array inputs for multicast events is up on the issue tracker. It seems like Epic is making this a priority and the target fix is for 4.20.1, so that is good. I’d still encourage anyone here to vote on it to decrease the chance of it being backlogged. The issue can be found here.
Hi Robin, the AI logic happens almost solely within the abilities. The only exception is if you’re using the ability system component from the advanced example map, in which case some minor stuff is done to compare the evaluation result from each ability and to generate cached arrays for pathfinding and tile safety estimation which are shared between abilities.
So to see the logic for moving and attacking I would recommend looking at BP_Ability_MoveAttack as well as the parent class BP_Ability. Look particularly at the AiActivate and AssesAbilityValue events.