Cannot add Apple Pay cards to Watch

I have a new iPhone 15 Pro Max and a new Apple Watch (model A982 Version 10.1 (21S67) but when I try and add my Apple Pay cards to my watch via the Watch App on my phone, I just get "Could Not Set Up Apple Pay - An error occurred while setting up Apple Pay".

I get this with both payment cards, and a different error when I try to add my BMW key when I get "Cannot Add Car Key - there was a problem adding this BMW key to Wallet".

All of this worked fine on my iPhone 12 and my previous Apple Watch.

All software is up to date.