Due to dataprotection restrictions, the app can only show incoming calls, but no caller details like phone number or name. If you are using an alternative phone app which publishes this information in the notification bar of your phone, it could still work.

The notifications are only displayed if there is a connection between the mobile phone and the Fire TV / Android TV. Since the connection is usually connected via a local IP address, the notification is only displayed if the phone is logged on to the local network.

After the first installation, you may need to restart your phone to fix this problem. Start the setup wizard again. It is important that your Fire TV / Android TV always gets the same IP address via DHCP. With many routers you can set this. Otherwise you can also give the Fire TV / Android TV a static IP address.

The notifications are immediately displayed on the TV when they also appear on the mobile phone. Many manufacturers have apps to reduce energy consumption.

To prevent this, disable the energy optimization for this app on your mobile/tablet. Also, the WLAN must remain active in standby mode.

The app can only forward the notifications if they appear on the phone. If they only appear on your phone when you turn on the screen, the power saving mode is too restrictive for the phone. If you are using a Google Pixel device, delays could occur because "Adaptive connectivity" is enabled.

If you enabled "Hide notifications on lock screen" within your system settings, the app are also not forwarded to the app.

On Google Pixel phone unfortunately Google decided for the sake of battery lifetime, to delay notifications and only show them when you turn on the screen. If you experience this issue, please see here for a workaround: https://www.androidauthority.com/google-pixel-delayed-notifications-3480868/

Under Settings of the Fire TV / Android TV App you can activate the option "Turn on screen on notification". Then the notification will also be shown when the screensaver is active. Please note that devices connected via HDMI CEC or the TV itself may also be switched on, or that your Fire TV will end the energy saving mode.

In this case, the "Interaction Mode" option is activated in the application on the mobile phone. The advantage of this option is that while the notification is displayed, you can open the app with OK and close the notification with Back/Exit. The disadvantage is that some apps pause the playback. In this case deactivate the "interaction mode" (deactivated by default).

Some phones from Xiaomi and Huawei reset the notification access on system level when the phone is rebootet or after some time. Unfortunately this is a bug of these firmwares. The app cannot change this value.

A solution which helped some users was to set the notification access directly in Android settings. If this does not help, reinstall the app and BEFORE starting the app, give notification access in Android system settings directly. Also it could help to add the app to not optimized for battery saving in system app settings. Also please enable app autostart in permissions.

More solutions described here:

https://dontkillmyapp.com/xiaomi

and here

https://www.guidingtech.com/fix-android-accessibility-settings-turn-off-automatically/

If you get the error message that the app is too old, it can be ignored. It has no effects on functionality. As Google removed the ability to show overlay windows on Android TV devices, the app cannot be updated in the Google Playstore.

Since Android 15 Google filters some messages with sensitive data. More information and a workaround can be found here:

https://www.androidauthority.com/android-15-two-factor-authentication-codes-3492585/