Unable to add national identifiers for terminated employees

Hi Team,

We are facing an issue where are not able to view "Add" button for following employees against National Identifier.

Please find below details on how we tried adding the NID.
Navigational Steps:
Navigated to My Client Group > Personal Details.
Searched for the terminated employee in question (40208, 40206, 40199)
Selected the employee and navigated to National Identifier Section, but the “Add” button was not available on the page.
User Role:

The user who is attempting to add the NID has a super user role and access to view all data.
Actions Taken:
Verified that the user account has the necessary permissions to edit terminated employee records.