I'm with
@lovinthehd on this one. I too suspect you don't have the Audio Setting correct on the PC. I do the same sort of setup on my Man Cave / Junk Room setup with my Main PC. It's running Windows 11 Pro but before I built my new PC I had it running on the old Windows 10 Box.
I have a GeForce GTX 1080 GPU, and run it into Dual Monitors and an old Denon AVR-S900W. (Yes => All at the same time!) But you don't do anything about the settings on the GPU. What Operating System do you run?
How to change sound output Windows 10 (HDMI, headphones, optical out)
We just went through this with another member
My PC won'[t recognize my Yamaha TSR-7850, help! but it seems his used receiver was faulty. If you read my comments, I even took my Windows 10 MSI Laptop and set it up using Windows 10, and took screen shots to show the steps.
Here's the HDMI Features added to standards over time, and ARC is in 1.4. See photo below.
View attachment 68863
But you will be better off going through the receiver via HDMI as you can play Tunes, without having the TV on.
I hope this is helpful.