volume_change event doesn't reflect external monitor

[hahuang65]

When my laptop is docked to a monitor, the volume is not change-able, and the INFO seems to either be empty, or 0.

It's empty when I do a sketchybar --reload.

It's 0 if I change the audio output back to Macbook speakers, then back to the monitor.

Is there a way to reflect that the current audio device is not the built-in speakers?