@elliot
Because the probleme appears only if you don’t modify any native fields like content, title…
If you create a new post/page/post-type (a draf) the probleme doesn’t appear (because the title is different than the saved title I think).
But if you edit a post/page/post-type without changing the title or the content or other native wp fields, the first time you click on the preview button all works fine.
But the second time you hit the preview button, the modification disappear and the save post/page/post-type is shown. And the next time preview works again and next time save post is shown… (yes it’s strange ><‘)
So on edit post/page/post-type without native wp fields modifications (title, content…) , once on two the preview doesn’t works and the “preview” show the saved post/page/post-type.
By the way our solution works with all post meta (not only ACF), like Yoast SEO plugin.
I’m french, so sorry if my english is a little broken :/
