start-process -Credential $Credential won't work when running from self service portal

start-process -Credential $Credential won't work when running from self service portal

But runs when running it locally "powershell.exe -File "c:\whatever\filename.ps1"
all the other parts of the script is running well so I won't bother posting the whole thing that grants and revokes Write access to local users while notepad is open. Here is the first line that collects the credentials, and the 2nd that is failing to run when running from store.

$Credential = $host.ui.PromptForCredential("Need credentials", "Please enter your username and password.", "NetBiosUserName")
Start-Process -Credential $Credential -FilePath C:\windows\notepad.exe -ArgumentList "c:\windows\system32\drivers\etc\hosts" -Wait

not a typo issue when entering username + pw 100%.