If you host your site on  "WP Engine", you may encounter some issues with empty carts when visiting the checkout page. This is due to aggressive page caching (which is a good thing!), but it can be easily resolved by requesting that WP Engine setup a special cache exception for your checkout page.

Step 1: Note down the slug of your checkout page from the general settings

Step 2: Submit a support ticket to WP Engine via their support portal and ask them to exclude your checkout page from the cache.

To make things really easy for you, feel free to copy and paste this sample ticket:

Hi!

My site runs the Custom Checkout Pages by FunnelKit (formerly WooFunnels) and we want  to exclude checkout pages from caching. The FunnelKit (formerly WooFunnels) support team has instructed us to ask you to place a cache exception on our checkout page.

Could you please add the URLs which follow this patter to the exception list?

http://YOURSITE.com/{put your checkout page URL here}

Thanks!

By default, the Checkout page's slug is "checkouts". If you had changed the checkout pages slug for any reason get the slug from FunnelKit (formerly WooFunnels) > Settings > General > Permalinks