azure automation – Adding multiple folders with Add-PnPFolder appears impossible in a Runbook

I have some simple code to add a couple of folders to a SharePoint Site library. Locally it runs smoothly in seconds, but in a runbook the same code runs increasingly slower, resulting in getting the runbook suspended. Looking at the error messages, it seems that somehow it even goes into a loop of repeating commands. Max. 3 folders are created. In Azure and local I have the same module ( PnP.Powershell 1.2.0)
Any tips are very welcome.

$dcSharePointRootUrl = ""
$SiteUrl = "13Test"
$credential = Get-AutomationPSCredential -Name "XXX" ;
$targetSite = $dcSharePointRootUrl + $SiteUrl
Connect-PnPOnline -Url  $targetSite -Credentials $credential 
$targetFolder =  "/sites/"+ $SiteUrl + "/Shared Documents"
Add-PnPFolder -Name "Technical proposal" -Folder $targetFolder
Add-PnPFolder -Name "Procurement" -Folder $targetFolder
Add-PnPFolder -Name "Engineering" -Folder $targetFolder
Add-PnPFolder -Name "Commercial proposal" -Folder $targetFolder

Error messages:
Add-PnPFolder : A file or folder with the name Documents/Technical proposal already exists. At line:16 char:1 + Add-PnPFolder -Name “Technical proposal” -Folder $targetFolder + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + CategoryInfo : WriteError: (:) (Add-PnPFolder), ServerException + FullyQualifiedErrorId : EXCEPTION,PnP.PowerShell.Commands.Files.AddFolder