Have noticed this on a number of models recently, and doing a search in the forum I notice that a similar issue occurs on windows (topic “surfaces disappear after mirroring”)
In a new file, I created a rectangle and then “extrudedcrv” to create extrusion. “Mirror” the extrusion using either the edge of the rectangle, or a different curve results in the resulting object missing it’s outer faces. However, if I click on the object to select, the lines denoting the edge of the extrusion are shown highlighted.
Software information
Software versions
Rhinoceros version: 5.0 Wenatchee 2013-10-28 (486)
OS X version: Version 10.9 (Build 13A603)
Plug-ins
/Library/Frameworks/3DconnexionClient.framework/Versions/A/3DconnexionClient
Hardware information
Computer hardware
Hardware model: iMac13,2
Processor: Intel Core i5-3470S CPU @ 2.90GHz
Memory: 8 GB
Architecture: Intel 64 bit
Video hardware
Graphics: NVIDIA GeForce GTX 660M OpenGL Engine
Memory: (null)
Screen size: 2560 x 1440
Displays: iMac
USB devices
None
Bluetooth devices
None
OpenGL information
OpenGL software
OpenGL version: 2.1 NVIDIA-8.18.22 310.40.05f01
Render version: 2.1
Shading language: 1.20
Maximum texture size: 16384 x 16384
Z-buffer depth: 24 bits
Maximum viewport size: 16384 x 16384
Implementation settings
Use texture compression: No
Appearance settings
Antialiasing: 4x
Mip map filtering: None
Anisotropic filtering: None