If you edit a content in a backend and the template in question has a cache-block, the preview won't be updated.

Steps to Reproduce

1. Change ezpublish.yml and set your frontend siteaccess to have legacy_mode: true
2. Edit your design Full\Article template and add a cache block around the body attribute

   {set-block scope=root variable=cache_ttl}0{/set-block}
   {cache-block keys=$node.contentobject_id expiry=0 ignore_content_expiry subtree_expiry=$node.node_id}
   	{if $node.data_map.body.content.is_empty|not}
   		<div class="attribute-long">
   			{attribute_view_gui attribute=$node.data_map.body}
   		</div>
   	{/if}
   {/cache-block}
   

3. Clear the caches
4. Edit an existent article, and change the body.
5. Preview
6. Go back to edit
7. Edit that article again, and change the body again.
8. Preview

You won't be able to see content changes this time