Hello again,
I still haven’t been able to get it working. I’ll post the images below showing the steps I followed, so you can check if there’s anything wrong with the setup.
Blueprint Creation (BuildingProp)
I also tried with the “Forcibly Structurally Supported” option enabled.
Tried with and without the “Do Not Block Buildings” option under Building, and also tested other Building Types.
Also changed: Collision > Collision Presets to BlockAll.
If anyone has a file with just a single cube that allows building on top and can share it for download, I’d really appreciate it. It would help me analyze and understand what I might be doing wrong.