Toolguy

Nope, I don’t get the box.
Could you try to lower the UAC level, see if it’s security related maybe?

Have you run the tool once, to accept the EULA?
(There’s also a parameter to validate that you accept the EULA on the command line)

I just tried to call psshutdown -r from an Administrator command shell, and after 20 seconds my Windows 10 (Pro / version 1803) did restart without asking me anything.

It’s probably something that is version specific, or maybe some hidden settings.

Can you take a screenshot showing the exact command line you used, what psshutdown displayed, and the actual windows dialog box?