Building static lights that suppress lighting

Thank you. I’m a beginner and I’ve never used the “Lightmap Density” view mode. Everything is blue. If I understand correctly it’s not good. But I don’t know how to fix it. The wooden floor is a BSP geometric shape converted to “StaticMesh”.

EDIT : On the StaticMesh of the wooden floor, I have “Overriden Light Map Res” by changing the value from 6 to 64 and the floor became green in the “Lightmap Density” view mode. As I write, I have just started a build and am waiting for it to be finished.

EDIT 2 : Build complete. This did not solve the problem.