Setup: Lenovo Carbon X1 connected via USB C to a Thunderbolt dock.
The dock is connected via DisplayPort cable to a monitor which has audio out
The speakers work in Windows and Ubuntu Budgie
USB headphones that are connected to a USB hub connected to the monitor work
The speakers are detected in all OS's and distros I have tried, and shown in the Audo Control Panel (They are greyed out in Kubuntu)
Ubuntu Budgie only plays sound through the external speakers if I set the Built In Audio to HDMI 4

The speakers are detected but play no sound in Solus Plasma and NetRunner Rolling (Arch). This is even after switching audio out to The ThinkPad Dock and trying various settings in the drop downs for the "Built-in Audio" and "ThinkPad Thunderbot 3 Dock USB Audio"