No S/PDIF Out from USB Audio

Hi Folks

I just got the S/PDIF output expansion board for my 2.1 Amp. After some failed attempts I managed to get a signal out of it. But only if I’m playing music from any source other than USB (bluetooth, line, etc.)
When playing music from my PC through USB, there is no signal on the S/PDIF board. Neither coax nor toslink.

Is there any way to get S/PDIF output expansion board to work when the signal comes from USB?