i am having two issues, which may be related

1. a number of objects (groups) are not showing up in the rendering (vray)
2. i keep setting a material color which then snaps back to some shade of grey. I can finally get it to stick and then when I open the model after shutting down, a bunch of the materials have gone grey again. no clue what's going on with it..

Thanks for your help in advance

I really like the interaction btw shadows and linework when working in a group in hiddeline - linework overlapping shadows inverts to white. Is this possible as a style?