【GAS】Flex message simulatorで作成したデザインが反映されない。

const LINE_ACCESS_TOKEN = PropertiesService.getScriptProperties().getProperty('LINE_ACCESS_TOKEN'); // アクセストークンをプロパティストアから取得
const SPREADSHEET_ID = 'SPREADSHEET_ID';// 実際のスプレッドシートのIDを入れてます
const SHEET_NAME = 'SHEET_NAME'; // 実際のシート名を入れてます

function doPost(e) {
  try {
    const json = JSON.parse(e.postData.contents);
    const event = json.events && json.events[0];
    
    if (event && event.type === 'message' && event.message.text === '予約確認') {
      const replyToken = event.replyToken;
      const sheetData = getReservationData();
      const replyMessage = createFlexMessage(sheetData);
      sendReplyMessage(replyToken, replyMessage);
    }
  } catch (error) {
    Logger.log('Error in doPost: ' + error.toString());
  }
  
  return ContentService.createTextOutput(JSON.stringify({ content: 'post ok' })).setMimeType(ContentService.MimeType.JSON);
}

function getReservationData() {
  const sheet = SpreadsheetApp.openById(SPREADSHEET_ID).getSheetByName(SHEET_NAME);
  const data = sheet.getDataRange().getDisplayValue();
  
  let availableSlots = [];
  data.forEach(row => {
    if (row[2] === '空き') { // C列が「空き」の場合を抽出
      const date = new Date(row[0]);
      const time = new Date(row[1]);

      const formattedDate = Utilities.formatDate(date, 'JST', 'MM/dd');
      const formattedTime = Utilities.formatDate(time, 'JST', 'HH:mm');
      availableSlots.push({ date: formattedDate, time: formattedTime });
    }
  });
  return availableSlots;
}

function createFlexMessage(slots) {
  if (slots.length === 0) {
    return { type: 'text', text: '現在、予約可能な枠はありません。' };
  }

  const bubbles = slots.map(slot => ({
    type: 'bubble',
    header: {
      type: 'box',
      layout: 'vertical',
      contents: [
        {
          type: 'text',
          text: '予約したい日付を選択ください',
          size: 'md',
          align: 'center',
          weight: 'bold',
          margin: 'lg'
        },
        {
          type: 'text',
          text: '（1つのみ選択可能です）',
          size: 'sm',
          align: 'center',
          gravity: 'top',
          margin: 'lg'
        }
      ]
    },
    body: {
      type: 'box',
      layout: 'vertical',
      contents: [
        {
          type: 'box',
          layout: 'vertical',
          contents: [
            {
              type: 'box',
              layout: 'horizontal',
              contents: [
                {
                  type: 'button',
                  action: {
                    type: 'postback',
                    data: `date=${slot.date}&time=${slot.time}`,
                    label: `${slot.date} ${slot.time}`
                  },
                  gravity: 'center',
                  style: 'primary'
                }
              ],
              justifyContent: 'center',
              alignItems: 'center',
              spacing: 'md'
            }
          ],
          spacing: 'md'
        }
      ]
    },
    footer: {
      type: 'box',
      layout: 'horizontal',
      contents: [
        {
          type: 'button',
          action: {
            type: 'postback',
            label: 'キャンセル',
            data: 'cancel'
          },
          height: 'sm',
          style: 'secondary'
        }
      ]
    },
    styles: {
      hero: {
        separator: true
      }
    }
  }));

  return {
    type: 'flex',
    altText: '予約可能な枠があります',
    contents: {
      type: 'carousel',
      contents: bubbles
    }
  };
}

function sendReplyMessage(replyToken, message) {
  const url = 'https://api.line.me/v2/bot/message/reply';
  const headers = {
    'Content-Type': 'application/json',
    'Authorization': `Bearer ${LINE_ACCESS_TOKEN}`,
  };
  
  const payload = JSON.stringify({
    replyToken: replyToken,
    messages: [message],
  });

  try {
    const response = UrlFetchApp.fetch(url, {
      method: 'post',
      headers: headers,
      payload: payload,
    });
    Logger.log('Reply sent: ' + response.getContentText());
  } catch (error) {
    Logger.log('Error in sendReplyMessage: ' + error.toString());
  }
}

    messages: [message],
  });

　Logger.log(payload);　//　<---

  try {
    const response = UrlFetchApp.fetch(url, {