Can anyone clarify Outbound Campaign JSON schema validation failure?

Anyone know why the Genesys Cloud Outbound API returns a 400 Bad Request when attempting to create a campaign via the ServiceNow Data Action? The payload adheres to the documentation, yet the validation fails on the contact_list object. Running this from the London region. Here is the exact JSON structure being sent:

{
 "name": "TestCampaign",
 "contact_list": {
 "id": "abc-123"
 }
}

The error message is generic. Is there a required nested field missing?

Pretty sure the contact_list object requires more than just an ID in this specific context.

Cause: The schema expects a full resource reference or additional metadata fields that are omitted in your minimal payload.

Solution: Include the name and status fields within the contact_list object to satisfy the validation logic.