Continuing the discussion from Autosave fails on particular drawing:
The blue color indicates there are exposed back faces. In the case of the wall, it’s because you’re missing the near face of the 3D shape. If you zoom in, you can see that.
There are other places where the faces are reversed. You should not be seeing blue faces in the model on 3D shapes. And painting the back faces with colors and materials isn’t an adequate solution for reversed faces.