Did you build light after putting it on stationary?
Yes absolutely.
In the end, I went to dynamic lighting because of this sort of thing.
You need a moveable skylight and mesh distance fields turned on. That’s most of it.
That will give you dark inside. If you still have weird shapes on meshes after that, tinkering with the ‘distance field self shadow bias’ ( mesh editor ) should help.
Read the docs is also useful, because some objects just don’t have a MDF, and you have to build it:
But this stuff is quite often a bit like black magic, it really depends a lot on your level, the meshes, yada yada…
Just checked and the image in my last reply shows how it looks with both a movable skylight and mesh distance fields on. i still can’t seem to get it dark like a basement.