Powershell unzip with shell.application not working when launched from windows service

Question

I have a deployment agent on a machine implemented as a windows service. Service is 32-bit and runs on windows server 2008R2 x64 SP1 with powershell V2. Powershell script requires elevation and to run under x64 because of dependency to powershell module
'IIS Administration'. To achieve this, the service starts a cmd file which in turn launches powershell x64 console:
C:\WINDOWS\sysnative\WindowsPowerShell\v1.0\powershell.exe "Start-Process C:\WINDOWS\system32\WindowsPowerShell\v1.0\powershell -ArgumentList '-ExecutionPolicy Bypass -NoLogo -NonInteractive -NoProfile -File C:\Temp\EndJobCmd\Install.ps1' -Verb RunAs"
This seems to work well. The problem I have is that the script has a sequence where it unpacks a zip file to a destination folder using shell.application, this works fine when triggered manually on the server or through the task scheduler, but when triggered
from the service it does not extract any files at all (cannot see any errors thrown by the script but it seems to continue to execute as it logs a successful message to the event log after finishing).
Unzip sequence looks like:
$shell = New-Object -com shell.application
$pkg = $shell.namespace($sourceFile)
$installDir = $shell.namespace($targetDir)
$installDir.Copyhere($pkg.items(), 20)
Any advice greatly appreciated. I have searched some and seen a few people with similar issue but have yet to find a solution.

Answer 1

If it's still actual, I managed to fix this with having CopyHere params equal 1564. 
So in my case extract zip function looks like:
function Expand-ZIPFile{
param(
$file, $destination
$shell = new-object -com shell.application
$zip = $shell.NameSpace($file)
foreach($item in $zip.items())
$shell.Namespace($destination).copyhere($item,1564)
"$($item.path) extracted"
1564 description can be found here - http://msdn.microsoft.com/en-us/library/windows/desktop/bb787866(v=vs.85).aspx:
(4) Do not display a progress dialog box.
(8) Give the file being operated on a new name in a move, copy, or rename operation if a file with the target name already exists.
(16) Respond with "Yes to All" for any dialog box that is displayed.
(512) Do not confirm the creation of a new directory if the operation requires one to be created.
(1024) Do not display a user interface if an error occurs.