Sleep mode does not turn on at correct time.

[Marrriiaa]

So I have the galaxy s21 ultra, and before the sleep mode used to work, but now I work a night shift job so I change the times/days and now on the days I don't work the mode does not turn on

I have it set to turn on at 11:00pm, but when 11 hits nothing happens, and than randomly while I'm at work it will turn on.

I deleted the times, started over and what not, but it's not working anymore.

Galaxy S21 5G 

[Lbjohn99]

I have the same problem. Since about April 25, 2025, if my screen is off, the sleep mode no longer turning on at my preset sleep time, and stopped turning off at my wake up time.   I have been using the sleep mode for many years, then it stopped working.  I have already did the clear cache, re create the sleep mode , etc.  The sleep mode will turn on if my screen is on.  However, the screen is obviously off at 5 am in the morning, so the sleep mode did not turn off at 5 am because the screen is off.   This is like the famous joke that a flash light does not work when there is no sunlight...