Bulk export job fails with 403 on digital channel metadata

What is the reason this setting causes the bulk export API to return a 403 Forbidden error when attempting to retrieve WhatsApp transcript metadata for legal discovery? The IAM policy grants full access to the BYOC bucket, yet the job fails immediately upon initiation.

{ "error": "access_denied", "message": "Insufficient permissions for resource: /api/v2/recording/bulk-export" }