workingdirectory does not work when verb is used

Using Start-Process, when Verb is used, the Workingdirectory option does not work, the new powershell always start in C:\WINDOWS\system32. Why is this? How can I do this without an extra cd command?

PS C:\> $PSVersionTable

Name                           Value
----                           -----
PSVersion                      5.1.14393.0
PSEdition                      Desktop
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.14393.0
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1


PS C:\> Start-Process -FilePath powershell.exe -Verb Runas -WorkingDirectory C:\ws\

# the new ps shell always in system32:

Windows PowerShell
Copyright (C) 2016 Microsoft Corporation. All rights reserved.

PS C:\WINDOWS\system32> pwd

Path
----
C:\WINDOWS\system32

Solution

As for the why - see the bottom of this answer.

As for an effective workaround (which does, however, require use of cd (Set-Location)):

Start-Process -FilePath powershell.exe -Verb Runas `
  -ArgumentList '-NoExit -Command "cd C:\ws"'

Venryx points out that if you want to apply this technique to calling a script file that is normally called with -File rather than -Command, you must switch to a -Command approach (given that the two parameters cannot be combined) that changes the location first and then (;) invokes (&) the script, script.ps1 in the new location, this example:

Start-Process -FilePath powershell.exe -Verb Runas `
  -ArgumentList '-Command', 'cd C:\ws; & .\script.ps1'

For a more complex example involving nested quoting, see this answer.

In practice - and the docs do not mention that - the -WorkingDirectory parameter is not respected if you start a process elevated (with administrative privileges, which is what -Verb RunAs - somewhat obscurely - does): the location defaults to $env:SYSTEMROOT\system32 (typically, C:\Windows\System32).

^{Note that this is not the -Verb parameter per se that's the problem, but its specific RunAs argument.}

The only case in which -WorkingDirectory is respected in combination with -Verb RunAs is if the program being started is PowerShell (Core) 7, namely pwsh.exe - whether you call from Windows PowerShell or PowerShell (Core) 7.

Whether there is a good technical reason for this behavior or whether this is a bug, I have no clue. Do let us know if you do.

In all other scenarios:

running as the current user as-is (the default)
impersonating a different user with -Verb RunAsUser (with an invariably interactive credentials prompt)
running non-interactively as a different user with -Credential <PSCredential>

the -WorkingDirectory parameter is respected.

However, if the (different) target user lacks the permissions to access the implied (current location) or explicitly specified working directory (via -WorkingDirectory), the current location defaults to C:\ in case (2), and results in failure of the Start-Process command in case (3).