Recording channel where source is USB


Hi all, I am having a hard time finding an answer to the following so posting here to see if anyone can help. Thanks in advance.

I have an MR18 I'm controlling from my Windows laptop. They're connected via ethernet for the MR18 controller, and USB for recording to DAW. Mixing and recording work fine. We're using 9 channels all with analog inputs and I'm using Acid Music Studio for my DAW.

I also have 1 input where the source is set to USB, to play audio from the laptop back into the mix. This works fine for the live mix, but it's not being picked up by the DAW for recording. In the DAW I set the input for the track to be the channel I've got the USB running through -- just like how the other DAW tracks are set up -- but it doesn't detect the audio.

All suggestions welcome.