Getting a 400 Bad Request when trying to send a proactive message to a user with a prior session. The GET /api/v2/conversations/messaging/contacts/{id} returns a valid externalId, but the subsequent POST /api/v2/conversations/messaging/contacts/{id}/messages rejects the payload.
{"to": {"id": "ext_123", "type": "external"}, "body": "Check this"}
Is the traceparent header stripping the to object? Here’s the snippet: