Are you using "Do not disturb"? If your wake alarm is set during your "Do not disturb" time then try #2 below.
Turning off "auto optimization" helped the first time then the problem returned. I'm not sure which of the following options helped the second time; however, once my mid-day & evening alarms were working again, I found that my morning alarm was now being stopped by "do not disturb".
1. Settings -> Device Care -> (menu) -> Auto Optimization -> (turn off)
2. Settings -> Notifications -> Do not disturb -> Allow exceptions -> Alarms -> (turn on)
3. Settings -> Apps -> Clock -> Storage -> Clear cache
4. See if creating a new alarm will work and have sound.
5. Does the timer in the Samsung Clock app work and have sound when it goes off?
6. Try a restart after changes
Hope that this helps.
Same happened to me many times. alarm of Note 9 isnt trustable. Twice I was late from my work. And three four times being at home. Samsung must fix this issue. This is v serious
Right now, I am using my old Galaxy S4 as an "alarm", because on monday i went 2.5 hours late to work.
I noticed on tuesday, that my Galaxy A70 with Android 9 HAS sound BUT it's VERY QUIET!
I tried everything to make it louder but unfortunately I couldn't find a solution yet.
If you have no second phone to use as an "alarm-phone", you could try installing and using the Google Clock app from the Google Playstore until this problem is solved.
I hope this will work for you.
(sorry for bad english )
I had this problem earlier in the year but it went away. Now it's back again and I've been late to work four times already. I've tried all the suggestions to fix it but nothing works. Samsung needs to address this ASAP.