Custom Payload not working in Google DialogFlow ES

I am sending a simple custom payload copied from official docs. Here is the payload ->

{
  "richContent": [
    [
      {
        "type": "accordion",
        "title": "Accordion title",
        "subtitle": "Accordion subtitle",
        "text": "Accordion text"
      }
    ]
  ]
} 

The intent is not attached to any previous intents, and I am not sending response through the backend. Instead, I am sending it through the "Response Section", built-in in the Dialogflow console.

The problem is that DialogFlow is not able to identify this custom payload, although the intent works alright when a text response is sent instead.

PS:- The scenario is the same when instead of using the built-in console, I send the response through the backend. Dialogflow understands simple text response but fails to process the custom payload.

Here is the screenshots ->

Your custom payload should work if you ran your test in Dialogflow Messenger Integration as it supports accordion response type. See test below using your custom payload:

Intent configuration: