Post Grid disappears (Visual Composer)

⛔️ Deprecated: This document only applies to WP Rocket prior to 2.8.15.
As of WP Rocket version 2.8.15, we have added automatic compatibility with Visual Composer's Post Grid. 

When using the Visual Composer plugin (and any plugin/theme that uses a nonce as described below), there are some modules, most notably the Post Grid, which require special attention when caching.

The problem

Seemingly randomly the post grid doesn’t load and you have a blank space on your page. After you clear the cache, the page displays correctly. 

The solution

In the Basic options tab of WP Rocket, set Cache Lifespan to 10 hours.

The cause 

The module from Visual Composer uses an AJAX call with a nonce to display your posts. That nonce has a limited lifespan and can expire in the background.
Read more on WordPress nonces and caching