May be it is fixed now.

It is working on my TVS-671. It wasn't working on my TS-569Pro .

I can not check TS-569Pro as it is in a different physical location far away.

Both are QNAP firmware 4.2.1 (20160601).

Main : C15, MD600, Aurender N10, EMM DAC2X, Boulder 865, Oppo BDP-95, JM Labs Maestro Utopia
Office : PC, Resonessence Invicta, HD800