I’ve had Apple Pay payments get rejected due to internet issues — make sure you’ve a solid LTE signal, not on dodgy wifi, and perhaps flip back to airplane mode temporarily next time it happens.
Thanks, was on LTE. Had no trouble interacting with either app, adding payment method, using the Internet, etc. It was just the payment being rejected. I think this had to be a common payment provider issue, and who knows what fraud detection flags I was triggering for whatever reason.