I have implemented postback button like

"payload":{
        "template_type":"button",
        "text":"Try the postback button!",
        "buttons":[
          {
            "type":"postback",
            "title":"Postback Button",
            "payload":"DEVELOPER_DEFINED_PAYLOAD"
          }
        ]
      }

Button is showing in messenger but when i clicked on it, it did not sent the payload to my API. If i type any message and send it, that message sending to my API. URL open and make a call by button click are working, only postback button is not working.

subscribe version for messaging_postbacks is v18.0, App Mode is Development and my app is not business verified.