How do I init an actor ref variable of a service in the behaviour tree window?

Hello dear community,

I’m using a behaviour tree to control my AI.

I have one service that control it senses which need a reference of an actor present in the scenes. This actor will change depending of which Behaviour tree implement this service. So I decided to make the variable editable in the behaviour tree.

I have the right value proposed by Unreal but whenever I click on on, the value stays on “None”. I tried to use the “Pick actor from scene” but I have the same issue.

Here is the setup of the variable :

What am I doing wrong, any ideas are welcome.

Thank you !