清单验证,但应用程序以空白屏幕打开?

我将首次向我的Web应用添加清单。我的清单在manifest-validator.appspot.com上成功验证。而chrome应用程序->Service Worker窗口显示Service Worker已成功注册。我可以在iPhone上“保存到主屏幕”。但是当我打开保存到主屏幕的图标时,我会得到一个空白屏幕。

这是我的myapp\u manifest.json文件:

{
  "short_name": "myApp",
  "name": "myAppLongName",
  "icons": [
    {
      "src": "images/app-images/myIcon-512-green_512px.png",
      "type": "image/png",
      "sizes": "512x512"
    },
    {
      "src": "images/app-images/myIcon-512-green_192px.png",
      "type": "image/png",
      "sizes": "192x192"
    }
  ],
  "start_url": "/?utm_source=progressive_web_app",
  "background_color": "#63aed5",
  "display": "standalone",
  "scope": "/",
  "theme_color": "#3367D6"
}

我错过了什么?