Is your subclient by any chance configured as a type: Full Recovery Model?

It should be None if you want to backup all types.

Quote:

"Subclient Type

You can create four types of subclients. Use these subclients for backing up different types of databases based on their recovery models.

Full Recovery Model - Use this subclient type to back up the databases where recovery model is set to full.

Simple Recovery Model - Use this subclient type to back up the databases where recovery model is set to simple.

System Databases - Use this subclient type to back up the SQL Server system databases like master, msdb, and model.

None - Use this subclient type to back up any database type."

Source: https://documentation.commvault.com/2022e/expert/61532_subclient_properties_general_sql_server_agent.html

Was this a log backup? Databases in simple recovery mode do not generate transaction logs. You’re not ‘not protecting’ them, there is nothing to protect. When you run a full backup those databases will be captured and the job will complete with errors if not

If you start using plans than you're issue will be covered automatically e.g. this is handled because it creates a full every day.
https://documentation.commvault.com/2022e/essential/130560_automatic_server_plan_backup_schedules_and_associated_conversion_rules.html

For reporting there are a few reports available, please look in the software store which is accessible via https://cloud.commvault.com

Some examples:
https://cloud.commvault.com/webconsole/softwarestore/store.do#!/135/660/13090
https://cloud.commvault.com/webconsole/softwarestore/store.do#!/135/728/23157

@DaveK

Yes this is expected since its not possible to run a tlog backup against a database in simple recovery model which is why it is skipped and not marked as failed. However you can change this behavior. Instead of skipping you can have these DB marked as failed which would help with your reports. There are setting in control panel.

https://documentation.commvault.com/2022e/expert/58638_sql_agent_configuration_sql_configuration.html

Mark skipped databases failed during backup

You can even control if the job will CWE using the conditions rules in control panel

https://documentation.commvault.com/2022e/expert/6189_customizing_completed_with_errors_condition_overview.html

Alternately if you want the backup to also protect those database during a tlog backup you can allow it to convert. In this case when a tlog backup runs those specific DBs which are in simple the backup will convert. That option is also in the control panel under “SQL Agent Configuration”

Allow transaction log backups to be converted for simple recovery model databases