Hi @Matt,
I am using a sandbox account and I have set United States in region column, I configured SettingsGeneralLanguage&RegionRegion to US. I have added test cards (VISA and Master) and my cards is successfully activated. But I am trying pay then I got error "Payment Not Completed". I have tried many approaches like make other sandbox user, change devices regions as US, but error same. Note: I am trying from India. I don't know any issue with the country.
Could you please help with that? Thank you.