Thanks for contacting support regarding this issue. I have gone ahead and enabled diagnostics mode for your account and what that will do is next time your Roon Core is active, a set of logs will automatically be generated and uploaded to our servers for further analysis.
Can I please ask you to first reboot the NVIDIA shield? Then, connect once again and reproduce this behavior that your are seeing and provide the exact local time in your country that it occurs at? This will help us cross-reference the times listed in the logs and see if Roon is displaying any internal errors at that time. Please let me know when possible.