Low lightning/lightmap problem

I am mounting a PAK file during runtime and opening level from it. It seems the lighting seems to be off. Like the lighting build Data is not applied.
What could be the problem. I checked files in PAK and build data seems to be in it.
I have also loaded assestresigestry.bin file

Heres image of thirdperson map i loaded with mounted PAK as you can see lighting problem in it.