Scheduled dark mode triggered when disabled

[ApolloZhu]

Originally posted by @owenzhao in https://github.com/ApolloZhu/Dynamic-Dark-Mode/issues/30#issuecomment-535287400:

I am using iMac 5K with no external monitor. Here is my settings.

If I am using my iMac at the sunset time, though I turned off the related settings, my system turns to dark mode at the very time.

Version 1.5.2 (1.5.2) macOS 10.15 Beta (19A573a)