I have installed elementary OS release-juno one week ago and i tried to enable night light but its not working, even in manual or sunset ~ sunrise time. how can i fix it ? did anyone else get this weird problem?
Try this: Wingpanel Nightlight Indicator https://github.com/elementary/wingpanel-indicator-nightlight
My problems regarding the night light is due to the use of dual graphical cards (optimus technology with nvidia) on my notebook, all I needed to do is to install the latest nvidia driver and it worked on the next reboot.
There are lots of details about that, you can either install bumblebee or
nvidia-prime, the latter I currently use. To make usage of that you have to type in your terminal:
sudo apt install nvidia-prime
Take a note, however, that this might be dangerous and you have the chance to get a black screen on the next reboot; in order to fix the problem you just log in another tty (Ctrl+alt+FX where x belongs to [1, 9] and remove everything related to nvidia.