The different result between actor being clicked and not

hello guys.
i am highly focused on unity for a while and now learning amazing unreal engine!
and of course got stumbled with really weird tricky problem here. need your helps!
the problem is the result is DIFFERENT when i am selecting actor or not when playing the level.

here is the actor
just simple using phx constraint.
moving it slightly to y axis so i can check how the physics constraint works.

but it ends up

i add the arrow for showing you guys what is happening here.
So Doesn’t matter, after playing, if i don’t click the actor in the scene, it Never Move!!!
And Once i select it the actor, it moves even though i deselect it!!!
what on earth is happening here.
any advices plz guys.