OTel context loss when sending Open Messaging quick replies

Trying to propagate a trace ID into Genesys Cloud’s Open Messaging API (POST /api/v2/conversations/messaging/{id}). The payload includes quick replies:

{"type": "quickReply", "payload": {"title": "Check Status"}}

The request succeeds, but the resulting conversation event in Jaeger lacks the parent span. I’m injecting X-Traceparent in the header, but GC seems to ignore it for outbound webhooks. Is there a specific header name GC respects for tracing messaging actions?