^ i think that's driver related. experienced this with a laptop with Intel HD Graphics. when i uninstalled the HDMI Audio drivers, then had windows re-detect the device and automatically install drivers for it, it only used a generic microsoft driver. only legacy audio formats were supported.
i re-installed the latest graphics driver package from intel, then the support for HD Audio formats were restored.
edit:
check in device manager and see if the driver provider for HDMI audio device is by microsoft. if it is, try re-installing the driver package from AMD.