SMS default country picker value ignored.

I'm setting up SMS MFA, the text messages get sent + the user can authenticate with them fine however I've set the default country in the portal to the UK (as that's where all my users will be) however when i actually go to test the MFA flow in the app, the default country is still the USA. I've reinstalled my app a few times, made sure i've clicked save and also waited a few hours however it still seems to be the case. Screenshots attached. Please could somebody help. Thanks!