Starbucks seems to have broken Amex support via Apple Pay…tried twice and got a read and then the terminal said DECLINED. Others have recently posted on Twitter, too. In my case, both times, nothing seemed to hit Amex's side of things. My BofA MasterCard worked fine.
In the past, Discover via Apple Pay never worked at Starbucks (much like Subway) where you'd get an EMV error or something similar. I suspect Amex breaking may be a tweak on Chase's end (they provide Starbucks with the payment processing).
I usually reload my card through the app, but I was buying gift cards and it failed. Has anyone else see this recently (or can report that it is working for them)?