Here is a quick example with some screenshots.
I've tried this with different patterns within the scripts and the parameter line, meaning placing single and double quotes in different locations to see if it was anything with the parsing of the text. No change in the error.
I'm told we are on version 0.2.2.4 - I have no idea of the current versioning of the product. I'm just the resident scripting guy.
The error I get in the Terminal Window is:
Sending script to agent .......
Script CMD = @powershell -NoProfile -ExecutionPolicy unrestricted -file "%windir%\temp\myPSScript.ps1 -identity "administrator""
Executing Script ...Processing -File 'C:\Windows\temp\myPSScript.ps1 -identity administrator' failed because the file does not have a '.ps1' extension. Specify a valid Windows PowerShell script file name, and then try again.
For the screenshots in one I commented out the parameter assignment and specified the variable value, in the other I am passing the parameter argument just as I would from a normal console.