Q802USB/Audacity not detecting cpu audio input on PC

Hey gang,

Pretty basic set up with a Xenyx Q802USB: XLR mic and a 3.5mm stereo jack to dual 1/4" cable  running audio from the computer to the board -- all of this connected to my PC via USB. The device is recognized by both my machine and Audacity -- input and output are both set to "USB Audio Codec"

I have the headphones split so that I can hear myself and the audio routed from my computer to the board. However, Audacity is only detecting my XLR mic audio. Nothing from the PC running to the board is being picked up. I have the correct buttons pushed down on the board for USB output ("To Phones" is pressed down, "To Main Mix" is up) 

I took this same exact set up to my MacBook and it worked with no issues -- Audacity was picking up my mic and audio I was running from YouTube.

Any reason why I'm running into problems on the PC?BPHS-1 AT headset with integrated XLR micBPHS-1 AT headset with integrated XLR micIMG_20200601_233546.jpg