Ugh… Nevermind… ^^;;;
I was using the StateTreeAI component on my character instead of a StateTree component. Apparently the component with the “AI” suffix is for use on an AIController, not on an actor/pawn/character. The naming suggested the “use this for AI logic” for me, but that wasn’t the case. My mistake. I’ll leave the post undeleted and answered, in case someone else has the same problem. 
