I started a map in 0.18 with the pitch black setting turned off, but now when I try and enable it I don't see any difference. Is this option only available when setting up the map?
I don't see why it would be, but the setting doesn't seem to work.

This is about as dark as it gets, which to me looks like just a normal night: https://imgur.com/mqKqdFo

Hello,

You should be able to turn the setting on or off at any time, in a running game, with no issues. I've tested this myself and it's working correctly for me - so it may be another mod interfering. Also, please be sure you're on the latest experimental, as there have been some bugs related to the API for this feature in earlier versions of 0.18.

If you can upload the save somewhere I can also take a look and see if I can find what might be wrong.

Ah it was a mod called Afraid of the Dark that was overriding the lighting. I was using it for the additional lamps and forgot it changed the lighting as well - disabling it fixes the problem. I should have checked that first, thanks :)

No problem - have fun!