Why does applying a discount code empty the cart at checkout?

Technical Q&A
1

We are using the Sunrise 2FD theme. I just set up a discount code for a spring sale. It is supposed to apply to a specific list of products and purchases over $100. Customers can add multiple items to the cart and then view the cart. Upon hitting “proceed to checkout” the cart is emptied and you get the checkout screen but an empty cart.

What am I missing?

Link to store - https://mysanjuanpools.com/discount/Spring2023

2

Update: It seems that the cart only empties when an item is added that cannot ship. We sell several products that cannot ship (hazmat) but are available for customer pickup. When any of these items are added to the cart and you proceed to checkout the cart empties.