Sketchup model missing materials in Vray

Hi - I’m a long time sketchup user but fairly new to VRay. I’ve just purchased a few plant models from Turbo Squid and am having problems getting them to render properly. The model looks fine in skp but half of it is missing in Vray.

What does the plant model look like in SketchUp, with the Monochrome style set?
Check that the faces are oriented correctly.
In Asset Editor, do the materials have a Diffuse Color texture?
What version of V-ray?

Model in SketchUp

Model in VRay. I eventually got the flower heads to show up correctly (their opacity was set to 0%) but I can’t seem to fix the leaves and stems, no matter what I try.

Show the plant in SketchUp with the face style set to Monochrome.