Windows 11 Powershell Null Get-CimInstance

Artemis23

here is the updated version of your script please check and update if you have further problems

$user = "RemoteDesktopUser"
$userDesc = "Remote Desktop"
New-LocalUser -Name $user -NoPassword -AccountNeverExpires -UserMayNotChangePassword -Description $userDesc | Set-LocalUser -PasswordNeverExpires $true
Add-LocalGroupMember -SID S-1-5-32-545 -Member $user
$Sid = (Get-LocalUser -Name $user).SID.Value

$assignedAccessConfiguration = @"
<?xml version="1.0" encoding="utf-8"?>
<AssignedAccessConfiguration xmlns="http://schemas.microsoft.com/AssignedAccess/2017/config" xmlns:rs5="http://schemas.microsoft.com/AssignedAccess/201810/config" xmlns:v4="http://schemas.microsoft.com/AssignedAccess/2021/config" xmlns:v5="http://schemas.microsoft.com/AssignedAccess/2022/config">
  <Profiles>
    <Profile Id="{$Sid}">
      <KioskModeApp v4:ClassicAppPath="%ProgramFiles%\WindowsApps\%RemoteDesktop%\RdClient.Windows.exe" v4:ClassicAppArguments="--kiosk https://www.contoso.com/ --edge-kiosk-type=fullscreen --kiosk-idle-timeout-minutes=5" />
      <v4:BreakoutSequence Key="Ctrl+A" />
    </Profile>
  </Profiles>
  <Configs>
    <Config>
      <Account>"{$user}"</Account>
      <DefaultProfile Id="{$Sid}" />
    </Config>
  </Configs>
</AssignedAccessConfiguration>
"@

# Use the correct namespace
$namespaceName = "root\Microsoft\Windows\AssignedAccess"
$className = "AssignedAccessConfiguration"

# Create a new instance if none exists
$obj = Get-CimInstance -Namespace $namespaceName -ClassName $className -ErrorAction SilentlyContinue
if (!$obj) {
    $obj = New-CimInstance -Namespace $namespaceName -ClassName $className
}

# Set the configuration using the appropriate property
$obj.Xml = $assignedAccessConfiguration

# Save the configuration
Set-CimInstance -CimInstance $obj