[JesperW]

There used to be a menu for selecting which one of the MXM maps was selected as the viewport preview map in Max.

How is that done now?

[misterasset]

The exact same way you would do it if it were a standard material. Click on the map in the Maxwell rollout and click the checker blue and white cube that tells it to display in the viewport.

[JesperW]

I see. Nice enough. I only wish this setting was preserved from the last version, now when I open an old model all previews are turned to grey and I have to go through the entire XRef hierarchy and reselect viewport bitmaps...