Which firmware are you using? Firmware 2.1.3 and below have an issue where network updates might stop after a few weeks of OpenSprinkler being on. A reboot usually fixes this issue. Also, check your location is a valid one with proper data. Not all weather stations are always up and have accurate data. So you may have to use the map feature to find a nearby station with accurate data.
Also, in regard to the sunrise/sunset times, the first day is the value on the controller (and the values used for the programs). The remaining days are calculated in the app and might vary just slightly from the controller times. With that said, it shouldn’t vary as drastically as you are pointing out. Therefore, I would suggest rebooting the controller and again checking the sunrise/sunset times.