Lighting a 3D Scanned Environment

I would like to use a 3D scanned mesh, of my flat for example, and use this as the environment for a game or VR experience. Either navigating a character through the environment or recreating the environment in virtual reality.

After importing in my scanned, textured mesh everything looks good until I try to rebuild the lighting, at which point the object just goes black. Even if I try adding a light source inside the volume of the environment. Does anyone know what’s causing this and how to resolve the issue please?

I also initially had a second problem that the scanned environment just appeared as a solid block that I was unable to navigate inside. I seem to have resolved this problem though, I think by setting the scanned mesh as with complex collision. But this still didn’t fix the lighting issue.