Architect Digital Flow Fails to Trigger ServiceNow Webhook on Text Channel

Having some config trouble here…

The send_email action completes, but the subsequent webhook action targeting the ServiceNow REST API endpoint returns a 500 Internal Server Error. The payload structure matches the Genesys Cloud documentation for Data Actions, yet the ServiceNow instance rejects the request. The flow executes without throwing a local error node.

flow:
 name: "Digital_Support_Intake"
 channels:
 - "text"
 - "chat"
 actions:
 - type: "send_email"
 template_id: "tmpl_12345"
 - type: "webhook"
 url: "https://instance.service-now.com/api/now/table/incident"
 method: "POST"
 headers:
 Content-Type: "application/json"
 Authorization: "Basic {{secret.auth_token}}"
 body:
 short_description: "{{conversation.text_summary}}"
 caller_id: "{{contact.email}}"
 urgency: "2"

The webhook test within the Architect UI succeeds. The failure only occurs when triggered by an actual inbound text message from a mobile device. Any ideas on why the runtime context differs from the test environment?