Thanks...fyi technical support posted the following:

Hi Clive,

Max content does not display in the terrain editor. To make this happen is not an easy fix, but it's something we are looking at for future development.

The workaround would be to create the terrain in Vue standalone and import the Max object. Work with the terrain in Vue, save the scene and open it from the Vue xStream menu in Max.

Best regards.
Lee Randall