CUI: Max vs Vray - Material Editor Sample Slots

[de-co1]

I want my sample slots in my material editor to display VrayMtl as defaults. In order to do this, we go to Customize > Custom UI and Defaults Switcher > Select Max.vray under Initial Settings for Tools Options.

Having done this, I ensure that under Assign Render (in Render Setup) I have Vray selected for both Production and Material Editor.

Why then do my material sample slots show up so dark it is impossible to work with my materials in this manner. They are not black and adjusting the sample slot multipliers doesn't help.

I have attached a screen grab comparing my 2012 version vs 2013 version. Graphics drivers for both are set to Direct 3D.

I could resort to display standard Max materials as my default. It would just mean an extra two clicks for each new material, but by rights this should work as intended. Using Slate material editor makes no difference.