The program preview (UI) and firmware use different scripts to calculate sunrise/sunset time, which may result in the difference. Also, if you are previewing today’s program, the UI will use the firmware’s sunrise/sunset time because those are variables the firmware will report to the UI. However, if you are previewing the programs for the next few days, the UI will use its own script to calculate sunrise/sunset time because the firmware does not keep track of the forecast sunrise/sunset times. To diagnose this further, the best way is for you to submit a support ticket with your controller’s configurations saved as a file, so we can import it and try to reproduce the issue on our end.