Lighting pitch black on BSP to static mesh after building

I’m trying to make roads for the intro of my game so I made a flat BSP box, converted to static mesh, applied texture and then grouped it together with other meshes (curb models). Every time I build my lighting the whole model is either completly pitch black or just doesn’t look right. I have a lightmass importance volume and a reflection capture, I’m not sure if this can be fixed as I heard that BSP to static mesh is just not very good. I’m rather new to Unreal and would appreciate any help with this, thanks :).