The error "Instance (or Volume) <ID> wasn't scanned properly" may appear in resource scan log and CPM server log if an instance, or volume is configured with the cpm backup tag key, and the tag value is empty. This message will appear only if the tag value had been previously configured with the name of a policy.
These two errors are related and will appear several seconds apart:
scan_resources(.\cpmserver\cpm\backup_tag.py:828) <instanceID>, tag parser error: Empty tag value. Please set policy name, or 'no-backup' to not backup resource (tag: )
Instance <instance ID> wasn't scanned properly (policy <policyName>)
To fix this issue, either configure the instance tag value to the desired policy, or enter no-backup if no policy is desired.
Another option; if tag based backup is no longer desired for the instance, remove the tag key cpm backup.