I think you’ll find it’s the scaling of the large cube giving most of the problems. Try reducing it a lot. Large meshes need very large lightmaps.
Also, unless you really have to, don’t use static lighting 
I think you’ll find it’s the scaling of the large cube giving most of the problems. Try reducing it a lot. Large meshes need very large lightmaps.
Also, unless you really have to, don’t use static lighting