Komischer BUG (the handle is invalid) mit Powershel in Verbindung mit VisualStudio (2019 Prof) C-Sharp CmdLets

[CmdletBinding()]
Param 
(
    [Parameter(Mandatory=$false, ValueFromPipeline=$true, ValueFromPipelineByPropertyName=$true)][switch]$Uninstall,
    [Parameter(Mandatory=$false, ValueFromPipeline=$true, ValueFromPipelineByPropertyName=$true)][Int]$Restart,
    [Parameter(Mandatory=$false, ValueFromPipeline=$true, ValueFromPipelineByPropertyName=$true)][string]$Priority = 'NORMAL',  
    [Parameter(Mandatory=$false, ValueFromPipeline=$true, ValueFromPipelineByPropertyName=$true)][switch]$Silent
)

PROCESS {
    if(-not $PSScriptRoot) {
        $PSScriptRoot = Split-Path $MyInvocation.MyCommand.Path -Parent
    }

    #region ---------------------- SET LOCAL VARIABLES HERE -------------------------------
    [string]$env:SourceFolder               = "$PSScriptRoot\Source"  
    [switch]$env:Silent                     = $Silent
    [string]$env:Priority                   = $Priority 
    [string]$env:DisplayName                = 'SAP GUI 1.3.4.675 with IXOS 10.5 and Business Explorer'  
    [string]$env:PackageAutor               = 'UserName'  
    #endregion

    #region -------------- IMPORTING MODULES and Set Start Values ----------------------------
    try {
        Import-Module "$env:SourceFolder\InstallTools.dll" -Global -Force  
    } catch{return 1}

    Update-Environment

    #endregion

    #region -------------- Holt alle Functions aus dem importierten Modul --------------------
    # Get-Command -Module InstallTools
    #endregion
    
    #region Examples / Hilfe zu finden in Toolset.psm1  Zeile 0 bis 73
    #===============================================================================
    # = = = = = = = = = = =     UNINSTALL-SECTION    = = = = = = = = = = = = = = = =
    #===============================================================================
    Uninstall-MSI -ProductCode {1234-1234-12343212-1234-1234} -Caption "meine MSI"  
    Uninstall-RegistryKey -KeyFile "$env:SourceFolder\meine.reg" -TargetSCope 'x64'  
    

    #===============================================================================
    # = = = = = = = = = = =     INSTALL-SECTION    = = = = = = = = = = = = = = = = =
    #===============================================================================
    if(!$Uninstall) {
    Install-MSI -FilePath "$env:SourceFolder\meine.MSI" -TransForms "<SourceFolder>\meine.mst" -Caption "meine MSI Installation"  
    ...
    ...
    }
    

powershell.exe -Executionpolicy Bypass -noexit -file "C:\___TestPackage\Install.ps1"