Yeah, the Windows implementation is annoyingly buggy. I've found the best way to force it on (or off) without going into the settings and toggling it again is to kill explorer.exe via Task Manager - when it restarts then the night light will apply properly again.

I have my suspicions the reason why it doesn't work consistently has something to do with power savings or hardware profiles or something, but i haven't been able to reproduce it consistently enough to open a bug report.