Post Grid Disappears - Visual Composer
As of WP Rocket version 2.8.15, we have added automatic compatibility with Visual Composer's Post Grid
For versions prior to 2.8.15, please follow the below instructions.
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.
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.
In the Basic Options tab of WP Rocket, set " Clear Cache Lifespan" to 10 hours.
The reason is that this module from Visual Composer uses an AJAX call with a "nonce" ( https://codex.wordpress.org/WordPress_Nonces) to display the posts. A nonce is a security token printed into the HTML. It's only valid for a certain length of time. When you have caching, the nonce expires in the background, but the code on the page is still there—referencing an invalid nonce, so then things break. After the cache is cleared, the code is regenerated and references a correct nonce again.