My boss has asked me to try to resolve a problem as a favor to one of his distributors. So, I have no experience with Magento....
On their front page, they have products which have "Add to Cart" links. When a user clicks on those links, they are taken to a empty cart page. The site is: https://www.cantabile-genesis.com/index.php/
They are running Magento 18.104.22.168. My research on StackOverflow indicates that the link should contain a form_key parameter, which it does.
So, at this point, I'm stuck.
Any suggestions would be more than welcome.