I’ve been experiencing this phenomenon where Dark Mode in macOS 10.14 Mojave reverts automatically back to Light Mode. I haven’t been able to isolate the cause. Has anyone experienced this and is there a known solution?
Well, I’m going to have to admit user error on this one. I use f.lux and the recent update includes an option for switching to the Dark Theme at sunset. Well, that was checked so at sunrise it was switching it to the Light Theme. I don’t know why this setting was on by default because I didn’t set it that way. But, oh well, maybe this will help someone in the future.