It annoyed me while on holiday that the Sunrise/Sunset complication on my Apple Watch stopped working. I've finally fixed it thanks to Sunset / sunrise Apple Watch not working:

sunrise/sunset on AppleWatch comes from the “clock” app not the “weather” app. … go to settings>location services>clock> SELECT “while using app”

Also set Precise Location.

@Miraz Clock doesn’t show up in my Location settings 🤔

@pratik Hmm. Settings > Privacy & Security > Location Services > … Clock …