I am currently facing an issue with Radiance for windows version 5.2. The command rvu does not seem to be working. Based on the picture below, when I entered the rvu command, it loaded for a few seconds before prompting for a new command. There was no image or any form of visualization appearing on my screen.
Did you send me an email about not being able to find the ximage command? If so, can you try where getinfo and where ximage (and I guess, where rvu too) in a command prompt? If in Windows PowerShell, the command is Get-Command ximage. This will tell you where your binaries are. It would be good to check that you have all of the Radiance commands.
If you run just rvu does it say rvu: fatal - missing octree argument? That might help debug.