Quick reply buttons not rendering in guest client

We’re trying to inject structured messages into an active chat interaction using the Genesys Cloud Open Messaging API. The goal is to push quick reply buttons that trigger webhook events for downstream processing in New Relic.

The API call succeeds with a 200 OK, and the text content appears in the transcript. The buttons, however, are invisible in the guest client. The payload looks valid according to the docs.

{
 "to": {
 "id": "interaction-id-here"
 },
 "content": {
 "type": "application/vnd.genesys.messages.quickreply+json",
 "quickReplies": [
 {
 "label": "Option A",
 "value": "option_a_value"
 },
 {
 "label": "Option B",
 "value": "option_b_value"
 }
 ]
 }
}

The endpoint is POST /api/v2/conversations/messaging/messages. We’re using the standard OAuth token flow. No 400s or 422s.

Has anyone seen this behavior? Is there a client-side configuration flag we’re missing, or is the type value incorrect for the current SDK version?