Discount disappears when buyers have to log in to use Shop Pay

[HollyHGC]

We've been running a sale on a special product (we normally sell signed books, but wanted to offer a deep discount on unsigned books). We publicized it with a link that autofills the discount code at checkout, but kept getting orders where people were ordering the unsigned book, but without the discount code.

One of these orders came in when I was sitting at my computer processing orders so I called the guy and he explained what happened: To use Shop Pay, he was forced to log in, and when he logged in, the discount code disappeared.

That's a pretty serious problem - there's no point offering a link that autofills a discount code if using your payment system makes the discount disappear.