Ok, this problem ended up being my fault. For the merchant I was just trying to buy from, they insist on a U.S. billing address for a U.S. credit card for US shipping. This detail was *not* on their shopping cart page — I only found this out by further poking around and following other links. So having ApplePay send me cryptic messages about updating a billing address was just a consequence of this particular merchant’s policy. Others had no problem with it.
The problem with the streaming service is that the streaming service severed its relationship with ApplePay, and I guess (?) I was notified about that at some point or perhaps everyone else knew this. I got generic notices from the service to update my payment method, and I just couldn’t understand why…since it had always been handled through ApplePay.
So only moral of this story — understanding cryptic messages from ApplePay—is to make sure that US merchants will ship to US addresses, given a Canadian billing address for a card entered into ApplePay
thanks again for your engagement with this.