I followed the instruction on Preparing your app to be the default browser or email client. I have acquired the permission from Apple. The entitlement is included in the provisioning profile. mailto is specified in URL Schemes.
But I downloaded my app from TestFlight and enter Setting > MyApp, the switch that could enable my app to be the default email app was not there. I have no clue what I did it wrong.
Does anyone know how to configure the app properly?