"Apparently, there was a significant change in Windows 10 version 1803, starting from which Windows no longer backs up the system registry. Registry backups will still show as successful, but backup files being created in the RegBack folder are now empty! Which really looked like a bug – up until last week, when Microsoft confirmed this was done on purpose and is intended "to help reduce the overall disk footprint size of Windows"."
Registry is a tiny (yet important) part of Windows - reduce footprint, when its only using a toenails worth if that ? :)