I would use “TryGetPawnOwner” in the AnimBlueprint to get the CharacterBlueprint Actor of the AI. The use “GetAIController” on that.
This makes sure that each AnimBlueprint is really using the values of its Character.
I assume your custom AIController class has a Blackboard component. Cast the result of “AIController” to your custom Class and
try to get the Blackboard Component from that.
I taked another way. In the blueprint create by the behavior tree, i cast to blueprint anime and set à blueprint anim variable. Now i take the control on the blueprint variable by the behavior tree.