Thanks for letting us know about the website issue you are experiencing.
We appreciate your patience regarding this matter. If you are unable to complete placing an order and the cart is still empty, there are a few things that you can do to resolve the issue.
Could you please verify if you go to the profile icon at the top of the page and are you are seeing "Welcome Back NULL"? If yes, we suggest signing out and signing back then please attempt to add the item to purchase and try to checkout again.
Let us know how it goes! We're hoping this will work for you.