Play one-off blendspace anim in a slot, in code

Still haven’t made any headway on this. Even trying to step through in blueprints, I encounter the same problem: there’s nothing to allow playing of a one-off blendspace that is properly animating over the upper body of my character. I can’t use any layered blend nodes or slots, as far as I can tell. Actually, I’m having issue with just stopping the animation, instead having the character stuck at the end frame of the played blendspace.

No one has ever needed to do something similar? Am I just making this way harder on myself than it needs to be?