Trying to send a quick reply card via the Open Messaging API. The basic text works fine, but adding the structuredMessage object returns a 400 Bad Request. The JSON looks valid to me. Here is the payload body:
{
"structuredMessage": {
"type": "card",
"title": "Check Status",
"actions": [{"type": "button", "label": "Yes"}]
}
}
The error message is generic. Is the schema different for guest-initiated messages?