Ahh okay, I get it. Neat concept. And truthfully all of that info was helpful and I understand a lot more.
So what I’m seeing is you should be able to do this by making the dirt blocks a real actor- not just a static mesh. Then you can give that actor collision to use for getting the spawn location of your next dirt block. If you have something like that going on and it’s just not detecting the static mesh actor you’re spawning, make sure it has collision and keep in mind it will be considered a WorldStatic object for purposes of collision.
Maybe show us how you’re getting the object to stack on?
Good luck! Hope this helps!