You can resolve some of the backup errors that appear in the Dynamics 365 Backup Health report.
Never Backed Up
If the client or entity was recently added, it's OK that it is not backed up yet. The client or entity will probably be backed up soon. If backups fail to run for a long time, create a support ticket.
Not Backed Up in Selected Time Period
In the Tables Not Backed-up table, under Failure Reason, the message explains how to resolve the issue. If no message appears, create a support ticket.
No Failure Reason or Message is Unclear
In the Tables Not Backed-up table, under Failure Reason, the message explain how to resolve any issues. If no message appears or if you do not understand the message, create a support ticket.