Did you try below in PW command window.
set PNUSER=login account name
Then run any PW command see the result.
Mostly the account that you are trying to access pw commands is not part of administrator. Login using an administrator account.
If you are logging in using the administrator account, then UAC might be turned on. Disable UAC.
Another thing you might try is right click and use "Run as administrator" and then try the pw commands.
Just in case....
The pw commands require a specific set of environment variables set up to execute properly. Are you trying to execute the commands from a regular command prompt, or are you opening the command shell by clicking the "pw commands" shortcut?