Solved. Montage Export - Render stopped working

Rendering a montage:
Today, out of the blue, when I select Render (menu or shortcut) nothing happens. As if I hadn’t touched the computer…
Any clues?

Windows 10
Wavelab 8.5.31 build 872 64bit

I clicked in the render button in the master section. Not only it worked but after that all was normal again.
Go figure…