No sound over HDMI on PC

[deusxm]

I'm running RecalBox off a USB stick on my PC, and although the system works absolutely fine, I'm having a problem with no sound output.

In the sound options menu, I've got a choice of three options - one headphone jack output, and two HDMI ones. None of these allow sound via the TV.

It's definitely not the cable, the TV or the PC. Usually I run LibreELEC on this PC, and I have three HDMI sound output options in the menu in LibreELEC - two are just 'HDMI' and don't work, but the third is 'HDMI' and then names my TV...and this one does.

Does anyone have any suggestions on how I could get sound to work please, or let me know what additional information I'd need to provide to help? Thanks!