API textTabs not populating

 Hi Everyone
I am new to DocuSign and currently integrating it with MuleSoft using the "Envelopes Post Envelopes" API. I am sending the following payload, but the envelope is not being populated with the data I am passing. However, when I include xPosition and yPosition, the data appears in the envelope. My goal is to populate the fields using tabLabel instead, but it is not working. How can I resolve this issue?
Template with Standard Text field
 

Payload:

{
     "brandId": "d380fe66-xxxxxxxxxxxxx",  
      "templateId": "63ebae68-xxxxxxxxxxxxxxxxxxxx", // Need full template ID
    "status": "sent",
    "compositeTemplates": [
        {
              "templateId": "63ebae68-xxxxxxxxxxxxxxxxx", // Should match above
            "sequence": "1",
            "inlineTemplates": [
                {
                    "sequence": "1",
                    "recipients": {
                        "signers": [
                            {
                                "roleName": "Signer1", // Match template role name exactly 
                                "email": "test@test.com",
                                "name": "TestSigner",                    
                                "recipientId": "1",
                                "tabs": { 
                                    "textTabs": [
                                        {
                                            "tabLabel": "FirstName", 
                                            "value": "John"                                           

                                        },
                                        {
                                            "tabLabel": "LastName",
                                            "value": "Doe"
                                        },
                                        {
                                            "tabLabel": "Email",
                                            "value": "test@test.com"

                                        }
                                    ]
                                }
                            }
                        ]
                    }
                }
            ]
        }
    ]
}

Thank you in advance!