Can you see why when adding a product directly from the category page it is automatically removing itself from the checkout sidebar – there seems to be a bug here.
When I add the product to the shopping cart from a category it is added correctly, then I go to the checkout and the product is still in the shopping cart. https://gyazo.com/2822d3fed571094f369bf0ba055a5737
I have checked in two browsers both logged in and logged out. Please describe the problem in step by step so that I could reproduce the problem.
Please check out the link – private content section. It shows what happens when you click on the “View basket” when you are trying to add a variable product to basket from a category page.
I have checked the same on the default theme and the problem is the same, it means that our theme does not influence. You will have to reconfigure the cache setting on your server.