Debugging BP-World Interaction

I have a level BP that opens a door as soon as the player enters its hitbox. Obviously that only works if the door transform is set to movable (which I learned after searching a bit). Now this is correct behaviour, but it took me a while to find out.

So how does one debug such BP-world interactions? Of course this issue in particular is fine now and I will hopefully not run into it in the future again. My question is more general: How does one start to trace such a kind of problem in Unreal 4?