I don't think I've *ever* heard of a defective pi that has working hdmi video and non-working hdmi audio (the physical pins used are the same for audio and video).
The issue if either going to be a configuration issue, or some incompatibility with the specific display.
If you have another hdmi display, please try that.
If you have no hdmi audio on a clean install of RPiOS, then try creating an issue here.
I try in another TV with HDMI, same result HDMI audio doesn't work and analogue yes. I have another SDcard with RPiOS installed and HDMI audio works perfect. I think with this result the more obvious is to think in some Libreelec configuration