Chrome app manifests ignored

Creating website shortcuts in Chrome through ⋮ > More tools > Create shortcut... creates an extension, with a manifest at ~/.config/google-chrome/Default/Extensions/xxx...xxx/###...###/manifest.json:

{
   "app": {
      ...
      "launch": {
         "web_url": "https://www.google.com/"
      }
      ...
   }
   ...
}

Editing the "app"."launch"."web_url" key does not change the target. Is the 'true' manifest stored somewhere else? Is it cached somewhere? How can I edit the URL target (other than by creating a new shortcut)?