I actually did reach out to Out of the Sandbox’s tech support a few months ago about this issue. Their knowledge was pretty limited, and they basically suggested the same advice as the shopify help page, i.e. removing the additional_buttons code from the cart page. Beyond that they said that the actual check out page, and its code was Shopify’s domain, and to check with them, or hire a shopify expert.
It was when I actually looked into getting a shopify expert, that someone suggested simply getting an app that allows the discount code to be entered on the cart page, as a work around. As mentioned earlier I installed an app called dcode that seemed to do just that, but as it turned out, the amount they calculated wasn’t actually passed on to Apple Pay. If anyone knows of an app that can actually do this, I’d really like to know.
It’s probably easier to do that, than hire a shopify expert to move the check out buttons, assuming that can be done as well.
Thank you
Dak