Light bleeding behind wall when GI Baking

I have a room made of separate gameobjects for each wall, ceiling and floor. When I GI bake the room, the light from outside is coming through the wall as can be seen the below picture.
I have checked for a proper intersection of walls, and they all are static, and tested with freshly created Cube Gameobjects, but still same issue. How to prevent that light coming though ?

Which lighting backend are you using? Make sure that your meshes and the light is set to cast/receive shadows.

Thanks for your answer. I’m using Progressive CPU and all meshes / lights are already configured to cast and receive shadows.

There must be something wrong with your scene setup. How does the Baked Lightmap scene view look like right after baking? Also, it would be worth checking how does Texel Validity view look as well.