Data Action POST 400 Bad Request - Missing Field Validation on Custom Object

How do I correctly to handle nested object validation in Genesys Cloud Data Actions for multi-tenant integrations?

Our AppFoundry partner application is currently experiencing intermittent 400 Bad Request errors when attempting to create records via the Data Actions feature.

We are deploying a multi-tenant solution that requires strict adherence to field validation rules.

The error response consistently points to a missing required field, even though the payload includes all mandatory attributes.

{
“errors”: [
{
“code”: “VALIDATION_ERROR”,
“message”: “Field ‘external_ref_id’ is required but was not provided.”
}
]
}

The request is authenticated using a valid OAuth2 access token with the necessary customobject:write scope.

We have verified that the field exists in the schema and is marked as required.

The issue appears to be related to how nested objects are serialized in the JSON body.

Is there a specific formatting requirement for nested fields in Data Action payloads?

We are using the latest version of the Platform API SDK.

Any insights into this validation behavior would be appreciated.

We need to ensure data integrity across our partner ecosystem.

Please advise on the correct payload structure.