Hi @Glen,
Could you please share a bit more about your scenario?
Could you please share more details about your issue?
Further, do you change the Dynamics connection to the app into another Dynamics 365 connection in your UAT environment?
Please check if the version of PowerApps Mobile App within your iOS device is the latest version (my version is 3.18111.14), if not, please upgrade it into the latest version, then check if the issue is solved.
Please also consider take a try to run your published app within a Android device, check if the issue still exists.
You could consider take a try to uninstall PowerApps Mobile App from your Mobile device, then re-install it, run your app again to check if the issue is solved.
Best regards,
Kris