Copying and pasting windows, walls, workplanes or any surface with a name will end in repeated names... that causes errors when exporting.
TILT field in IES files (for exporting luminaires) does not work.
Radiance multithreading is not supported on Windows
Some windows users have had trouble assigning the Radiance path. I have been told that was solved as follows:
Go to 'Control Panel' > 'System' > 'Advanced' > 'Environmental Variables' and check if the Radiance PATH is correct. If not, fix it.
Then input the PATH in the Groundhog Preferences menu as follows: C:/Program Files (x86)/Radiance/bin, that is, with "/" (not "\") and without adding any program name.