When I copy and past from one SU file to another (only in this one case) it copies into
new file in another axis so that is all that can be seen is a thin line.
I notice the the axis lines have different orientations from one file to the next.
When you copy the geometry from the SOFFIT SKP into the REFLECTED CLGS file, it will come in with its orientation matching the axes of the REFLECTED CLGS file.
The easy fix would be to either rotate the pasted geometry or rotate the geometry in the SOFFIT file so it is oriented to allow the Top view to be used instead of the Left side view.
If you are going to continue making these 2D models in SketchUp, I would suggest that you set up your default template so the camera is set to Parallel Projection and the standard Top view. Then all of your models will be drawn in the same orientation.
Here I’ve rotated the geometry so it can be seen from the Top view.