[Kazun]

Пустые значения нельзя передавать, можно $null.

Код:

$prop = Write-Output EMail Phone Organization JobTitle
Foreach ($CurrentUser in $Users) {
	$Name = $CurrentUser.Name
	$Surname = $CurrentUser.Surname
	
	$prop | Foreach {
		if($CurrentUser."$_") {
			Set-Variable -Name "$_" -Value $CurrentUser."$_" -Force
		}
		else {
			Set-Variable -Name "$_" -Value $null -Force
		}
	}

	$path = $CurrentUser.Path

	$Login = Get-ADuser $Name | Set-ADUser -EmailAddress $Email -MobilePhone $Phone -Company $Organization -Title $JobTitle -PassThru | Move-ADObject -TargetPath $path
}