You know I don’t know!? I just grabbed a cube and scaled it to size, I’ll check that.
If it’s a brush, you need to lower the resolution value. Default is 32. You can try 8, 4 or 2… But still better to have a static mesh with high res like 1024 or 2048 for the floor. I would use 2048!
Geometry from unreal editor (cone, sphere, box etc) are usually used for blocking out a game level before artists create the proper static meshes in another 3d soft!!!
don’t use those : 
It is just a basic cube not a BSP, are those still bad to use?
Should be fine then. It’s set to static and not movable?
This is from official doc https://docs.unrealengine.com/latest/images/Engine/UI/LevelEditor/Viewports/ViewModes/VM_LightmapDensity.jpg the only grey-ish part is the character. It’s because it’s movable (thus not being affected by lightmass baked lighting)
Where do I check to see if it’s set to static? Under mobility it says static.
