Per the issue, we suggest pls delete the shield in our app at first, then Unbind X1 & shield, pls go to the setting of your nvidia device and unbind the sofabaton X1 hub in bluettoth option as well.
Then Close your Shield(Unplug Shield and restart), exit the sofabaton APP
You can wait a few minutes to open the app and add the Shield again, at this time you need go to your device setting, find the bluetooth option, and manually pair the sofabaton x1 hub again, pls check if the problem still exists after you try above steps
This is a reference video of how to unbind the firetv and U1, you can see it for reference, steps are sinilar, tks: https://www.youtube.com/watch?v=e0cjH5Qz6QY