I doubt that's the case though it's a valid fact. The terminal will complete the transaction and ask what type or print a receipt once it goes through.
@Toes Up My experience with WearOS has been similar to yours, frustrations because of what should be simple things not working. In the Galaxy Wearables app on your phone, did you go into Samsung Pay section for the watch and make sure a address is attached? I've had quirky things happen when adding to my watch. Seemed like it was 'easy' just to find sections not filled out properly.
Another possible cause could be any sort of adblocker. I fought with AdGuard devs for months to whitelist a Samsung domain in their non-togglable filter (baked in) that was blocking Samsung from syncing. I never even tried my Watch 7 to be honest.
Btw what is your phone ?
:edit: nvm, I forget what I even own. I have a Watch 5 Pro. Almost had a 7 until T-Mobile rep got