Anchor String not populating value from JSON payload

Hello Everyone,

I have a quick query regarding the anchor string feature of DocuSign. I have a web app that allows users to select documents to preview them first. If everything looks good, they can proceed with e-Signing.

To achieve this, I have set up two templates in my DocuSign account:

1. Preview with Viewer role: This sends the envelope to the current logged-in user for previewing. If everything looks correct,
2. The user can then proceed with the e-Signing process using the second DocuSign template with the Signer role.

Everything is working in the flow as expected, except for the part where the user wants to preview the envelope. The user is receiving the envelope, but the documents within the envelope have empty anchor string values. However, when the user actually sends the envelope for e-signing(Signer Role), we can see that the anchor string values are populated correctly in the documents under the envelope.

I'm wondering if this is by design, or if there's something I'm missing or doing wrong while populating my anchor strings for the Viewer Role.

{
  "status": "Sent",
  "compositeTemplates": [
    {
      "serverTemplates": [
        {
          "templateId": "f3XXXXXXXXXXXXXXXXXXd6cebf",
          "sequence": 1
        }
      ],
      "inlineTemplates": [
        {
          "sequence": 1,
          "recipients": {
            "signers": [
              {
                "email": "svashishth@ABC.com",
                "name": "Northern LLC",
                "roleName": "Viewer",
                "recipientId": "1",
                "tabs": {
                  "textTabs": [
                    {
                      "anchorString": "<<Project Name>>",
                      "scaleProperty": "SizeToFit",
                      "locked": "true",
                      "value": "Test Center"
                    },
                    {
                      "anchorString": "<<Test>>",
                      "scaleProperty": "SizeToFit",
                      "locked": "true",
                      "value": "Test Comment"
                    },
                    {
                      "anchorString": "<<Test Tag>>",
                      "scaleProperty": "SizeToFit",
                      "locked": "true",
                      "value": "Test Tag Comment"
                    }
                }
              }
            ]
          }
        }
      ]
    }
  ],
  "emailSubject": "Please sign this document"
}