Rhino7 display curiosity

the first image shows an exhaust modeled in Rhino7 with the “shaded” view option selected:


with NO other changes other than selecting the “Rendered” view option I end-up with some tubes displayed “transparently”:

what do I need to do differently to have all the tubes displayed the same?

Art
artesmith@earthlink.net

Hi Art, I saw that in the file you sent me, I’ll take another look.

-Pascal