Root Issue: I've owned the Samsung A15 5G (SM-156U) for two weeks now and have noticed that, at Midnight, the clock widget on the Home Screen fails to advance the date, causing the alarm to fail to go off the following morning.
Symptom: The clock alarm fails to go off in the morning because the date associated with the expected alarm has not arrived yet ... because the date failed to advance at Midnight. Oddly, the time/date on the Lock Screen and within the clock app is correct. Only the date on the Home Screen widget fails to advance at Midnight, and that causes the alarm to fail in the morning. AM/PM Time of Day is always correct on all screens.
Workaround: I have two alarms set up. I have a Mon-Fri alarm and a Sat/Sun alarm. I've found that when I toggle the upcoming alarm OFF then ON after Midnight, the date on the Home Screen widget corrects itself. For example - if it's Fri night and Midnight had just passed, the Home Screen widget is still stuck on Friday. I have to toggle the Sat/Sun upcoming alarm OFF then ON to force the Home Screen widget to advance the date to Saturday. Toggling the Mon-Fri alarm has no effect in this case. If I fail to toggle the correct alarm after Midnight, the alarm WILL fail to go off the following morning.
This same issue occurs with the stock Samsung clock and now with Google clock. It happens when Time/Date/Time Zone is set to Automatic or Manual.
Of course I've checked relevant volume settings and settings related to alarm functions with system volume as well as gestures which I've heard could affect the alarm function. None of the suggested actions have changed the symptoms of the problem at all. Besides all this, the root cause has been isolated to the fact that the Date shown on the Home Screen clock widget fails to advance at Midnight.
I'm living with my workaround for now but am providing the above info for someone who may better understand the inner workings of the phone's clock/alarm functions. Maybe some bug in the code will be easier to locate with the given details.
