If your device is not available in the app and you are not sure what your device shows, because you do not see it, you possibly lost connection with device. When you are near LaMetric Time, try to check if LaMetric Time is available again.
In order to be able to manage your LaMetric Time your phone and the device need to be connected to the same network. Please check.
Also please try to reboot your phone and LaMetric Time and make sure your software is updated to the latest versions.