Set-ACL "Attempted to Perform an Unauthorized Operation"

As I have the same issue I had a bit of a closer look. The interesting thing is, that other tools (Windows GUI, icacls.exe) are essentially working with the same permissions.

My "guess" is, that Set-Acl is always setting also the owner of files & folders, which is officially not supported - in here ( https://learn.microsoft.com/en-us/azure/storage/files/storage-files-identity-assign-share-level-permissions?tabs=azure-portal ) MS writes:

"""

Full administrative control of a file share, including the ability to take ownership of a file, requires using the storage account key. Full administrative control isn't supported with identity-based authentication.

"""

As you always apply a full ACL object to Set-Acl it always contains ownership information and maybe it's thus always setting the owner (even if it hasn't changed).