Override Material Greyed Out?

[Joelaff]

What causes the Override Material box to be greyed out and unselectable? I am seeing this here, and even see it in the screenshot in the docs. Still on the last version of VRay5 at the moment.

Thanks.

[Joelaff]

Oops. I am an idiot. The mouse clicks on the checkbox seem to require you to click for a long time for some reason, but once checked it works... Duh.