Help - Nuendo Live can be heard on USB channel connected to Yamaha TF5


Our PC is connected to a Yamaha tf5 mixer via USB cable. At times when the Band is playing, I need to record one or more channels with Nuendo Live, the problem is that the selected channels will play in the speakers over the USB channels on the Mixer. Then when I deselect those channels (from Nuendo Live) they stop being played. The PC is important to be heard because occasionally we play key pads in the background so clearly I can’t have the PC channel turned off on the mixer.

I honestly don’t know what’s the cause of this because I did try to mute the sound output from Windows and that’s not the issue. It probably is something in the communications between Nuendo Live and the Mixer. Can anyone help me please?