A parent object record that is referenced in an inactive Simple Join object relationship is still available to be selected when creating a document that uses this object relationship in Vault.
This is working as designed. In a Simple Join object relationship, what matters is the status of the opposite parent object record that is selected. If that object record is inactive, then it is omitted from the list of available object records.
The solution is to do one of the following:
- Inactivate the affected parent object record, instead of the object relationship
- Delete the affected object relationship
Vault Object Documentation: About Object Relationships