Если вы удалите messenger_extensions и fallback_url из вашего JSON, все должно работать нормально.
Используя пользовательскую полезную нагрузку в диалоговом потоке, все поддерживается, пока вы отправляете правильный соответствующий канал json
Вот рабочий проверенный пример карусели (несколько элементов)
{
"facebook":{
"attachment":{
"type":"template",
"payload":{
"template_type":"generic",
"elements":[
{
"title":"Welcome!",
"image_url":"https://upload.wikimedia.org/wikipedia/commons/7/70/Example.png",
"subtitle":"We have the right hat for everyone.",
"default_action":{
"type":"web_url",
"url":"https://www.google.com/",
"webview_height_ratio":"tall"
},
"buttons":[
{
"type":"web_url",
"url":"https://www.google.com/",
"title":"View Website"
},
{
"type":"postback",
"title":"Start Chatting",
"payload":"DEVELOPER_DEFINED_PAYLOAD"
}
]
},
{
"title":"Welcome!",
"image_url":"https://upload.wikimedia.org/wikipedia/commons/7/70/Example.png",
"subtitle":"We have the right hat for everyone.",
"default_action":{
"type":"web_url",
"url":"https://www.google.com/",
"webview_height_ratio":"tall"
},
"buttons":[
{
"type":"web_url",
"url":"https://www.google.com/",
"title":"View Website"
},
{
"type":"postback",
"title":"Start Chatting",
"payload":"DEVELOPER_DEFINED_PAYLOAD"
}
]
},
{
"title":"Welcome!",
"image_url":"https://upload.wikimedia.org/wikipedia/commons/7/70/Example.png",
"subtitle":"We have the right hat for everyone.",
"default_action":{
"type":"web_url",
"url":"https://www.google.com/",
"webview_height_ratio":"tall"
},
"buttons":[
{
"type":"web_url",
"url":"https://www.google.com/",
"title":"View Website"
},
{
"type":"postback",
"title":"Start Chatting",
"payload":"DEVELOPER_DEFINED_PAYLOAD"
}
]
}
]
}
}
}
}