eshop proceed to checkout link empty’s the shopping cart!

Hello,

I am running the latest version of eshop and have a very big problem. When I add an item to the cart and then click the proceed to checkout link, I am taken to the shopping cart page with the message “your shopping cart is currently empty.”

Here is a link to the site: https://www.oilcreekoutfitters.com

I have no clue what has happened as I have changed nothing and this has been working like a charm until now.

Can anyone please point me in the right direction so I can correct this issue? Thank you very much.