I have a Ultech smart dual usb c to hdmi hub and I have two external monitors connected and can get them to display fine. When I try and switch the audio to one of the external montiors via the volume control I get no sound. Only one of the two monitors will display as an external sound output. Either monitor will work when plugged into a single USB C to HDMI connector but never when plugged in to the dual setup. I have tried the Selore USB C to dual HDMI connector as well. Any thoughts?