Sorry to hear that. Try to avoid the USB-to-HDMI adapter:
Sometimes audio output options change after HDMI firmware update. Maybe you can use DP for A/V afterwards. So if you can run Windows somehow, install the latest HDMI firmware, and see what it does to your DP output.
The cable is already up to date, it's this cable.
I had no problem with version 11 of LibreElec (not on the same PC though)