Unable to apply an instanced Material to a BSP Brush Item?

Hello fellow unreal engineers,

i have stumbled accross a problem i cannot explain to myself so i’m asking you for help or advice.

i created a master material with a lot of stuff in it, diffuse map, normal map, height map, metallic/roughness/occlusion as well as some parameters and tiling options. all works as expected, i can create instances of the material and set up like i want it to be. i can also apply the materials to static meshes, no problem at all.

however i just tried to create a level with the bsp brushes, like for example a box. and now comes my problem:
i cannot assign the material to the box. or more precisely, i can assign it. it shows up in the details panel.

but it is not rendered onto the object. the object looks like this checkboard material.
am i doing something wrong? i can assign other materials to the box and they seem to work, however when i then
reassign my instanced one, or any of the instanced ones i created already, it will not be visible on the object.

please help =)

it seems i have found, not quite an answer, but other information regarding the workflow of level creation and bsp.

the information i found was that you can (and for performance reasons also should) convert a bsp to a static mesh
when you are done designing it. i have tried this after assigning a placeholder material (non instanced) to it and aligning it
the way it should look. so after converting to a static mesh there were two problems which had to be solved manually.
the object had no collision and the lightmap index was set to 0 which caused weird lighting and a warning. i could fix both in the mesh editor.

however a new problem emerged then: the newly created mesh refuses to create a navigation area on top of it!?

any advise please?

i even tried exporting it to fbx and reimporting it, yet no change. also i restarted the editor and rebuild the whole level multiple times with no success. i have another mesh which i imported from blender, when i rotate it to look like a floor and scale it it immediately starts to generate the green nav mesh ontop of it. however the created mesh from bsp brush does not.

i found a bug report about this from 2015. the person stated that after reloading the editor it would work. i had tried reloading but had not moved the mesh afterwards. when moving it after the complete reload it will generate nav mesh as expected. weird that this is still not solved …