Command to run after backup

OS type and version Ubuntu Linux 20.04.6
Webmin version 2.021
Usermin version 1.861
Virtualmin version 7.7 Pro
Theme version 20.21
Package updates All installed packages are up to date

since virtualmin 7.7-2 my post backup command does not run as expected, have you changed something else when fixing the bug ?
If I use :- vmin->BackUp and Restore->Scheduled Backups and hit the backup button both backup in the background & foreground work as expected but left to run on schedule it fails the command.
I have set a cron job up with the post backup command to run much later than the scheduled backup which also works fine so I am at a loss to workout what is wrong, any ideas ?