How do I add the "E" prompt to a movable object after I aim my crosshair in it?

Great so seems you have problem over here

image

seems it is returning null. Make sure you are passing correct reference to component here

When this event is called (True) your UI turns visible and tries to find owner of this in level (location) to display promp. If can’t find it, it gives error.

When status is (false) UI is coillapsed-invisible and does nothing.

Try to make sure the interaction variable not empty.