Uniti Core Stop Playing After Resuming from Standby Occasionally

Occasionally, when the Core is resumed from standby, it won't play music at all.    The app still functions to browse the music database and select albums and songs normally.  The Core just doesn't play the music (by pressing the Play button in the App) I select.

To put the Core back to normal, I need to press the power button on the Core to turn the device OFF, and then wait for a few seconds to turn it ON again.

It happened more than a dozen times since I purchased the unit 2, 3 months ago.

Wonder if any Core user encountered the same problem.

Is it a software bug or hardware issue ?