Can't connect via HDMI

[AceCalhoon]

I'm attempting to connect to a desktop PC using a discrete graphics card over an HDMI port.

I have my XReal glasses connected to an HDMI->USB-C adapter, similar to the goFanco adapter referenced in the README. I can launch PhoenixHeadTracker and hit connect, and when I do it reports Connected... But roll/pitch/yaw all show zeroes.

If I connect via USB-C, I can get roll/pitch/yaw values, but no picture (the discrete graphics card isn't connected to the USB-C port).