confirm dialog not popping up on selecting datetimepicker

Question

After sending the following payload to SlackClient's chat_postMessage, when selecting the datetimepicker that appears, no confirm dialog pops up. Instead, a response is immediately sent back.

{
  "fromUsername": "NA",
  "channel": "NA",
  "iconEmoji": "gear",
  "text": "testing datetimepicker",
  "blocks": [
    {
      "type": "section",
      "text": {
        "text": "testing datetimepicker",
        "type": "mrkdwn"
      }
    },
    {
      "elements": [
        {
          "confirm": {
            "confirm": {
              "text": "Confirm?",
              "type": "plain_text"
            },
            "text": {
              "type": "plain_text",
              "text": "this is text"
            },
            "deny": {
              "type": "plain_text",
              "text": "Deny?"
            },
            "title": {
              "type": "plain_text",
              "text": "This is a title"
            }
          },
          "initial_date_time": 1690554480.0,
          "type": "datetimepicker",
          "action_id": "NA"
        }
      ],
      "type": "actions"
    }
  ]
}

Using confirm dialog successfully works with datepicker and timepicker. I've tried using an input type block, but that didn't work either.