I'm just curious to know what could be causing the total cost at checkout to be undefined.
Below are 2 screenshots. The first one shows that the cart knows the total (before shipping) cost of the order. You'll notice that the Payment section just says "P" - any idea why?
This screenshot shows the undefined problem.
My site uses a Free Shipping ($0) option, UPS (see in picture), and PayPal's New API. I have enabled the OPC Extension called "PayPal New API support"
If I disable One Pay Checkout, the checkout system works fine. When it's enabled, I get undefined.
I'm a bit tech-savy but new to your product. Any help would be greatly assisted. I can even give you a developer access if necessary.