I re-read the question several times, and I think this may help:
Then you can play your animation.
Sorry for the over-complicated explanation on how to do this in behavior tree.
It seems you want to just be able to do this in the level blueprint. That’s not as extensible, so you’d likely run into issues with this approach if you were to scale the project, but for what you’re asking I think this would work.
The ai perception would likely detect the character immediately after line of sight is set to false, making it true again, though…