I found a bug in the mini-cart:
You add products to your cart - then in the mini-cart you click "Proceed to Checkout" - then immediately click on "View and Edit Cart".
The result is - a empty cart.
I've tested the issue with v2.2.3 till v2.2.6 - result is every time the same.
Uploaded a video to dropbox so that you can see the behavior: https://www.dropbox.com/s/945yyoezh48h386/WhatsApp%20Video%202018-10-19%20at%2012.18.21.mp4?dl=0