Collision detection only working one-way?

I’m having a problem getting collision detection to work between my grid tile actors and a test obstacle actor I’ve drafted up real quick. Each grid tile actor has a box collision component that is supposed to detect if anything is occupying that space, but it doesn’t appear to be working. The obstacle BP itself is able to run a collision check and store a reference to the current Tile actor, but running a collision check within the Tile BP yields no results. Here is a pic of how I have both the Obstacle BP and the Tile BP set up.

And this is the result. As you can see, the Obstacle actor successfully detects its overlapping Tile actor, but none of the Tile actors detect any collision and prints out “Empty!”

Am I missing something obvious? I have both box components, one for each actor, set to OverlapAll and generate overlap events.