Does macOS Mojave support NightShift on external monitors? After upgrading to Mojave, I could have sworn I saw Night Shift kick-in on my external 4K BenQ monitor. But no more. 

Did I dream that? Or is Mojave supposed to be capable of supporting Night Shift on external displays? If so, might it stop working because of sleeping/waking and/or attaching/detaching the monitor?
Night Shift is working on external monitors in Mojave.

Sometimes Night Shift deactivates itself on the external display when you wake the system from sleep. (Maybe a Bug?)

Just reactivate it manually.


If Night Shift is off, go to the Night Shift tab in System
Preferences>Display and check the box labelled Turn on until
tomorrow.
If Night Shift is on, click on the Schedule menu in the Night shift
tab and choose  ‘Off.’
Use the color temperature slider in the same window to control the
degree to which colors change when Night Switch is turned on or off.