Some meshes are still black even with no overlapping UVs

Hello, I am very new to unreal and have this problem. I’m on unreal engine 4.20, and some of my meshes are still appearing as black even with no overlapping UVs, a 2k light map resolution and a spacing of 0.5mm between each light map when unwrapping in 3ds max.
There are other parts that are dark as well, but not black, and show the reflections too much since they are supposed to be white.

The photo attached shows what I’m talking about. The black wall is supposed to be white like the far wall. And the stickers on the glass door and the black frame are not reflecting properly as well. All these objects have the light map settings mentioned above.

Just in case it helps: i switched on planar reflections because i couldn’t get the reflections on the floor correctly; the uv maps were simply flattened in 3ds max using unrwrap uvw, i have no idea how to create my own uv maps.

Any help would be great.

Thanks,