I have had some backups fail recently (my fault; low disk space), but the problem is that while MSP360 reported the backups as 'Failed', the email notifications showed 'Completed with Warnings'.
This is happening across multiple clients and backup jobs.
Another, related issue is mis-reporting of failed files; I had a couple of files blocked by antivirus (false positive), but while the backup report told me that, it showed 0 files missed: