I'm happy to report that my bank has gone back to allowing Garmin Pay cards to be added to my Fenix 7xSS. There was a period of time where they were not authorizing new cards to be added and it looks like Garmin Connect now has a two-factor authorization where you enter a texted code when adding cards. So I suspect the issue was back end improvements. While I'm glad for this return to form, it support and communication around these changes was not great to be polite.
Anyway glad this feature is available again for Wells Fargo in the U.S. I decided to try it again after a few months of being unable to add it when there was an email advertising Garmin Pay sent to me by Garmin. Looks like they are making more effort in this area.