As explained in our documentation:
https://docs.servicenow.com/bundle/madrid-servicenow-platform/page/product/configuration-management/task/t_MakingAFieldRecommended.html

"a derived class is set with the recommended fields that are defined at the parent level. You can add or remove recommended fields for a derived class, setting it with its own recommended fields, without affecting the recommended fields at the parent or sibling levels. If all recommended fields for a derived class are removed, then the derived class automatically derives the recommended fields from its parent class."

While the recommended fields configuration inheritance works as explained, there is no easy way to prevent a child CI class with no recommended fields config from inheriting the parent config. Customer's may find that deleting the recommended field from the child CI in CI Class Manager will not work as a refresh will show the field appearing again.

Example:

1. Navigate to CI Class Manager
   2. Choose Computer -> Health -> Completeness -> Recommended Fields -> Add "Assigned to"
   3. Choose Linux Server - > Health -> Completeness -> Recommended Fields-> remove "Assigned to" - > Save -> Refresh

In this example, the result is that when the Completeness Score Calculation job finishes running, Linux Server CI's with no "Assigned to" value will be flagged as incomplete in the CMDB Health Dashboard even though the administrator only wants the computer CI's to be evaluated and not Linux Servers.

When there is no recommended field configurations for a child CI class, it will inherit the parent CI class's configuration. This is the current design and expected behaviour.

The best way to remediate this situation is to create a recommended fields config for the child class to override the parent configuration. Choosing a field that we know would be populated for all the child class CIs (such as "class") will give the desired effect of making those items not fail the recommended scorecard.

Given the example provided earlier in the description, the solution would be the following:

1.Go to
https://<your-instance-name>.service-now.com/cmdb_recommended_fields_list.do
2. Click on New
3. Fill out the following:
Table = Linux Server [cmdb_ci_linux_server]
Recommended Fields = Class
Active = true
4. Save

6. Run the CMDB Health Dashboard - Completeness Score Calculation job
https://<your-instance-name>.service-now.com/sysauto_script.do?sys_id=cfbb4ba1d7001200c1ed0fbc5e6103a6

At this point, Linux Server CI's will no longer be flagged as being incomplete.

Further to the above, an enhancement request has also been created for our product team to consider adding in a feature (i.e a checkbox) to control whether recommended fields should derive from the parent CI class in future releases. If this feature is important to you, please feel free to also create an enhancement request via HI to increase demand.