The missing section cut faces are due to what I suggested in your other thread. Incomplete loops of edges. You can see where I’ve hidden the doors that there are no faces in the openings. They need to be there to get the section cut face. You get them in places like on the outside walls because you’ve drawn edges across the ends of the interior walls which creates internal faces.
You’ve got a lot of reversed faces (all the exposed green ones in my screen shot (except inside the interior walls. Those should be corrected.
There’s incorrect tag usage…
And a load of unused stuff to purge…
If you set the camera back at a bit of a distance while the Camera is set to Perspective and then go to Parallel Projection, you shouldn’t see the clipping.
SketchUp is designed to be used with the camera set to Perspective. Parallel Projection is normally intended for output only.
I’m not sure why but you have the camera focal length set to 36mm which is pretty wide and will create some distortion. Maybe you want it that way? It doesn’t help you with keeping the camera back at a reasonable distance for the Parallel Projection views, though.