copy-vmguestfile does not copy all files

I have downloaded the ADK localy on a file server and I want to copy this folder, including subfolders and files to a VM.

Here is my command-line

Get-VM -Name 'MyVM' | Copy-VMGuestFile -Source \\fileserver\sharename\ADK -Destination 'C:\temp' -LocalToGuest -GuestCredential (Get-Credential -Credential 'Administrator') -Force

However, there is a subfolder named Installers with 221 files and the Copy-VMGuestFile cmdlet only copies half of them without any seeable logic behind...

Did I miss something or is this a bug?

I use PowerCli v11.3.0.