After GPU lightmass my mesh light is not correct

hi everyone,when i build lighting use gpu lightmass,after then the light of mesh is not correct,it depended on distace like this

close it:

far distance:

when i use cpu build light ,it is always ok
so how can i fix it!

I fix it.I just untick volumetric fog in exponentialheight fog,then build light,and again tick volumetric fog,build light,it is just ok
so anyone know why???