We disabled Apple Pay after several hundred users signed up, paid, but couldn't login. Turns out there's a lovely default feature that allows you to hide your email address when using Apple Pay, causing the account to be linked to a nonexistant email address, with your actual email address impossible for us to know/store. We've been working through manually rectify the situation on a per customer basis. Really guys, you've been so patient on this and we're extremely grateful. Thank you.