Missing geometry in one viewport

Hello, Im wondering is someone can tell me why the geometry is missing from the top viewport in this file?
RickLamp on Bureau.3dm (14.4 MB) Missing geometry.pdf (749.1 KB)

The geometry is not missing - you are just looking at the two cylinders edge-on. Surfaces have 0 thickness. In Rendered display mode, the surface edges are not shown, so you see nothing. If you need to see surface edges in Rendered mode, you can turn them on…

Thanks very much. That did the trick!