I'll take a look, but this sounds like it is by design. The day/night counter is stored in the sim. If you save it at night, then re-load it, it will still be night. If you save it with X cycles to go before sunrise or sunset, then reload it, it will still take X cycles until sunrise or sunset. Sunrise and sunset don't happen on nice round numbers of cycles unless you start the sim from 0 with day/night cycles enabled from the beginning.