SetFileSecurity Error When Copying DACL, SACL etc

[ghasty]

File copy works fine but an error message occurs when copying DACL, SACL, Owner, Group, (SetFileSecurity).
The target is a Synology NAS shared folder that I can see I have full access to.
I'm running v13.6.

ERROR_PRIVILEGE_NOT_HELD. A required privilege is not held by the client. [SetFileSecurity]

Robocopy copies them over successfully.

Has anyone else had success copying DACL, SACL etc with Synology?
I've NEVER had an issue with FFS copying ACLs to other NAS vendors.

Any help GREATLY appreciated!

[ghasty]

Unfortunately, after years of using FreeFileSync, I'm going to have to find another product. I need real support and can't wait forever. It was a good run.