My iPhone XR and ROKU Ultra are on the same network. When I attempt to start screen mirroring from my phone the Airplay passcode prompt appears on the TV screen and a dialogue box opens on my phone. It says enter the on-screen Airplay code for Roku Ultra. No keyboard pops up, so there is no way to type in the code. I’ve restarted the iPhone, the Roku, but nothing works. Help please!