I just decommissioned my 2011 iMac and replaced it with a 2018 Mac mini and a new 27" monitor. The iMac is where I used to play audio and controlling from the keyboard (F10 - F12) was never a problem. I am now connecting to the new monitor via HDMI (v1.4). It will play audio, but I can't control it from the keyboard - I get this instead:
When I go to the Sound in System Preferences, this is what I see for output:

This leads me to believe that connecting via display port might possibly give me the ability to control via keyboard? I can't seem to get a USB-C to mDP cable to send a signal, so I'm guessing I need Thunderbolt 3 to mDP. Does anyone know if that will work before go and buy the cable?
Any other tips that may work for getting control of the audio on the keyboard when connected via HDMI v1.4?


