Setting BSP material in blueprints

I want to change the material of a BSP brush in-game by using blueprints. Is this possible?

Attempting to set the material has no effect, no matter what element index I provide. I tried indexes 0-6, and nothing changed. Can BSPs just not be modified by blueprints? If so, is there a way to simply hide/show the BSP via a blueprint?

What you want to do is not possible. BSP is not meant to be permanent part of a level anyway.

You’ll need to turn it into a static mesh, which you can do from the “Brush Settings” category in the details panel (Hit the little down arrow at the bottom of that category).