The backup script ran at 02:00 every morning, a brittle cron job brittle as old wiring. The monitor showed a single red line: "regback copy not working." No error code, just the blunt message that meant everything might be different come Monday.
[Insert deadline for resolution]
If you are trying to use the folder to restore your system and finding it empty (0 KB files), this is likely not a bug. Since Windows 10 Version 1803 regback copy not working