Try the provided steps and test the app after completing each one:
- Check if the TV volume is set extremely low or muted.
- Check if the sound is working from other non-app sources such as TV channels, etc.
Note: If there's no sound from other sources besides the apps, refer to the no sound section of the BRAVIA TV troubleshooting guide instead.
- If there's no sound while casting, restart the casting device.
- Restart the app.
- Sign out and then sign in to the app again.
- Update the app to the latest version using the Google Play™ Store app.
- Reset the app.
- Perform a power reset on the TV.
- Update the TV to the latest software.