title: Sanity preview not working when I add or change content in Sanity Studio
body: <p>I've been trying to get live preview in Sanity to work for several days now, without luck.</p>
  <p>It works like a charm when I follow this tutorial:
  <a href="https://www.sanity.io/blog/how-to-quickly-set-up-a-gatsby-js-jamstack-website-with-a-headless-cms" rel="nofollow noreferrer">how-to-quickly-set-up-a-gatsby-js-jamstack-website-with-a-headless-cms</a>.</p>
  <p>But when I create a starter blog like this one: <a href="https://www.sanity.io/create?template=sanity-io/sanity-template-gatsby-blog" rel="nofollow noreferrer">sanity-template-gatsby-blog</a>, it does not work at all.</p>
  <p>I've followed three tutorials, but it always fails, even if I do exactly the same.</p>
  <p>This is my gatsby-config:</p>
  <pre><code>module.exports = {
    plugins: [
      &quot;gatsby-plugin-postcss&quot;,
      &quot;gatsby-plugin-react-helmet&quot;,
      {
        resolve: &quot;gatsby-source-sanity&quot;,
        options: {
          projectId:&quot;nt51j1jx&quot;,
          dataset:&quot;production&quot;,
          token: &quot;ABC123&quot;, //this is a dummy for this post
          watchMode: true,
          overlayDrafts: true
        },
      },
    ],
  };
  </code></pre>
  <p>When I create a new post and click &quot;web preview&quot;, <a href="https://i.stack.imgur.com/Z4L3k.png" rel="nofollow noreferrer">I get a 404</a></p>
  <p>It does not help to click publish, and I can't see any changes on the local host.
  Changes to existing posts are also not visible.</p>
  <p>I have to restart the server every time I want to see the changes. That's not the case with the first template I mentioned, but that one crashes when I try to install Sanitys code-input plugin, which I need.</p>
  <p>Thanks in advance!</p>