This appears to be a recurring issue with the AirPlay2 support.
1) Verify you have the latest AirPlay support:
A) Using remote: Home 3x, Up 2x, L, R, L, R, L (AirPlay should be 1.14-104 or later)
B) Settings/System/System update/Check now (should be 10.0.0-4209 or later) - try again
2) Verify your devices arent connected to a Guest SSID or otherwise have AP/Client Isolation enabled on the SSID - try again
3) Disable & re-enable WiFi on the Apple devices - try again
4) Restart all devices (Rokus, Apples, modem/router/gateway) - try again
5) Reset the paired devices: Settings/Apple Airplay and HomeKit/Require Code/Reset Paired Devices - try again
6) Setup HomeKit: Settings/Apple Airplay and HomeKit/Setup HomeKit - try again
7) Switch either Rokus or Apples from 5Ghz to 2.4Ghz, or from 2.4Ghz to 5Ghz - try again
😎 Manually configure Roku's display output to 1080p: Settings/Display type/1080p TV - try again