Agent Scripting Webhook failing with 400 on ServiceNow Incident Creation

Quick question, has anyone seen this weird error? with an Agent Scripting Webhook.

The flow triggers correctly in Architect.

ServiceNow returns a 400 Bad Request.

Payload validation passes in Postman.

Using Genesys Cloud API v2.

ServiceNow version is Washington DC.

The JSON structure matches the REST message definition.

Any ideas?