If you build lighting, you can’t move anything. The moment you move something, the lighting for that object switches to moveable, and you have to build the lights again, because the system doesn’t know what it should look like.
The seams in the walls is a classic static lighting problem. You will find many articles on here about that.
Do you have a importance volume around everything?
In the lightmass settings indirect lighting scale to 0.1-0.15 and 0.6 for smoothness.