While we work through solving this issue, here is a bit more information and what to do if you encounter this while placing a reservation:
The bug seems to be isolated to the Safari browser on IOS and OSX. After the Add to Cart selection is made, the refresh screen renders incorrectly with the empty cart notification at the top. If you scroll down the page you will see Go to Cart and Checkout selections. If you proceed to checkout you will see the reservation is actually in the cart and you should be able to proceed from there.
Let us know if you still encounter difficulty with the checkout process and we will do what we can to assist you.