Well interesting. Resetting the options seems to have fixed it. I'm now able to save the grey scale. Really strange. Before resetting, I looked all through the options and couldn't find anything that might have been causing it. Still a bit of a mystery, especially since I hadn't changed anything in the options since the install.

Long as we're here, one unrelated question: Scale issues. I've been in Vue since 5, and a lot of the plants I've acquired over the years are all over the board with their default scale when loaded into a scene. Is there any way to correct for this, or is it just the way it is with the changes that have happened to Vue over the years? Also, what unit sizes do you use? I've got the default now of 1 Vue unit is 1 meter.