Need Help!!: sun light pass through the walls and flickering when navigating in viewport

I am new to UE5. I am using geometry brush to create an inner box and a outer box. the inner is set to brush type ‘substractive’ results in a simple room like this:


then i create several windows using the same substractive way:

now the sunlight behave very wired : it pass through the solid wall and flickering show in my room when i navigate or rotate my camera view.
sunlightglitch

this is absoutely some glitch, but i don’t know how to fixed this so that the sun light behave more stable instead of coming and going unexpectedly when navigate in the room.

Any feedback would be appreciate, thanks!!