Content appears in preview then disappears after page loads

Based on the video you shared, this looks like a classic issue where content loads initially and then disappears after the page finishes loading. This was a common problem with older Next.js preview implementations from around 2022.

Important note: The preview approach you're likely using (usePreviewSubscription from older versions of next-sanity) has been replaced with modern alternatives. The current recommended approaches for previewing draft content in Next.js are:

1. Visual Editing with Draft Mode - The modern approach that provides live-as-you-type updates with clickable overlays
2. Live Content API - For real-time content delivery without complex preview setup

However, if you're still working with the older usePreviewSubscription pattern, the most common cause of content disappearing is:

Parameter name mismatches - Your GROQ query expects a variable name (like $slug) but your subscription hook is passing a different parameter name. When the subscription takes over from the initial getStaticProps data, it runs the query with incorrect parameters and returns null.

For example, if your query is:

*[_type == "page" && slug.current == $slug][0]

Your subscription params must use slug:

const { data: page } = usePreviewSubscription(pageQuery, {
  params: { slug: data?.page?.slug }, // Must match $slug in query
  initialData: data.page,
  enabled: preview,
});

Other common causes from that era:

• Initial data structure mismatch - Passing the wrong shape to initialData
• Missing or incorrect authentication token for fetching draft content
• Browser blocking third-party cookies if Studio and frontend are on different domains

My recommendation: If you're starting fresh or can refactor, migrate to the modern Draft Mode with Visual Editing approach. It's more reliable, better maintained, and provides a superior editing experience with live updates as you type. The old usePreviewSubscription pattern had various quirks that have been solved in the current implementation.