Add-PnPDocumentSet creates a regular folder, but no document set?

Hey there

I'm new with pnp and I'm quite inexperienced, but I'd like to add a new document set in a library with the following pnp command.

I can see that the content-type I define (in this example "Test Document Set") is being created - which is a document set. However, it is only creating a normal folder - not a document set.

 

Add-PnPDocumentSet -List "Documents" -ContentType "Test Document Set" -Name "Test"

 

Any ideas why?