Cintiq 16 prevents audio to other HDMI devices

Using the Cintiq 16 (not pro) with a Mowsil 4x HDMI splitter with 3 connections: PC -> HDMI in HDMI out 1 -> Samsung 55" classroom display HDMI out 2 -> Cintiq 16. The issue is that the splitter and TV audio device are removed from the list of audio devices in Windows 11 device manager, when the Cintiq 16 is connected. Therefore external audio cannot be selected. Audio plays (quietly) through the PC built-in speakers only. The audio works fine to the TV through the splitter when the Cintiq 16 is unplugged. Tried several other HDMI monitors and only connecting the Cintiq 16 will disable the other HDMI audio devices. All other devices coexist happily. Any known workaround for this issue please?