This is how it should be and this happens suddenly after playback stops. 
During playback you can see the play symbol coming up each few seconds keeping nuimo alive. Approx. five seconds after the last appearance of the play symbol Nuimo goes asleep.
So my question is: Can you restart playback after fife or 10 seconds after music stops. Try to stop playback with the Nuimo and after 10 seconds press the Nuimo. Playback should continue.
Please let me know
Best DrCWO
Edit:
Please let‘s discuss further in the rooNuimo tread as it is off topic here.