Symptoms

Starting in London release there is an option to remediate de-duplication tasks using out of the box remediation. This will remediate these tasks using the Identification and Reconciliation engine. 

When using this, it deletes not only the duplicate CIs but the master CI that was selected. 

This also does not happen with every single de-duplication tasks (If it happens with every single one, then it might not be the issue here)

Release

London and Higher (but could happen in lower versions as well depending on how you remediate your de-duplication tasks)

Cause

Asset and CI both have cascade delete rule on each other – you delete CI it deletes the corresponding asset , you delete asset it deletes the corresponding CI 

In the scenario there are say 2 duplicates each pointing to same asset record 

Ci Asset field on CI 
X. A1 
Y. A1 

While the CI field on asset A1 is say Y 

In the remediator if you pick X as Master and opt to delete the rest , Remediator deletes Y , which in turn cascade deletes A1 , which in turn cascade deletes X too. 

The issue is being seen for de-dupe tasks where the same asset is referenced by multiple CIs and the CI referenced by the master is not selected as the master. 

Resolution

2 potential solutions:

1. If the user can identify such scenarios they will have to pick the CI as the master that is referenced by the asset. Again there might more variations to this scenario where i suspect this might not always work. 
2. Choose not to delete the CIs but mark them as retired/ change name / remove asset reference 

Additional Information

We do not fault the tool for this issue. Having duplicate CIs referencing same asset records seems a deeper data issue than just duplicate CIs. If the same steps where done manually instead of the tool we would see the same outcome.