[Samsung Galaxy S10 Guides, News, & Discussion] McHenry_kramer:
Loaded U1 SAU Unlocked on AT&T S10: Notification Sounds and Vibration Eventually Stop

So I have the U1 variant SAU working on my AT&T S10 with a Verizon SIM with no issues except one.

After initial setup all notification sounds and vibrations work fine. Call ringtone always works with sound and vibration. I have all notifications set with popup, sound and vibration. These all physically work.

However, after a little while different app notifications start coming in without sound or vibration. They popup, but there is no sound or vibration. My connected Gear S3 notification works when these notifications occur on the phone without sound or vibration. When connected to a bluetooth speaker and a notification comes in for any app, the sound from the speaker will mute/lower when the vibration and sound should be coming from the phone. It won't even play through the speaker, but something in the phone knows to lower the volume of the music to allow the notification sound to be heard. I have tried uninstalling and reinstalling apps. This sometimes fixes the issue, but is soon returns. Resetting all phone settings will make the notification sound and vibration work for all apps, but then the issue starts to return for different apps at different times until they all have no sound or vibration. Factory and hard reset have the same effect, just with more work to get the phone setup again. I tried not loading the backed up phone settings, but there is no change and the sound and vibration work initially for all apps regardless of setting import or configuration.

I have given apps all permissions available, which after a settings reset has to be done for some apps to get the sound and vibration to work. I have tried disabling all optimizations of which I am aware: battery, storage, memory, and whatever I could find that hinted at some kind of optimization.

Seems like I had the same issue on my S8 and maybe even my S7 and disabling battery optimization fixed the issue with notifications, but I don't remember if it was the exact issue then. Perhaps, the app notifications didn't work all together because the app was "optimized".

I went through all settings and scenarios possible with Samsung support and they, of course to me to go to a Samsung store.

I would appreciate any help. I can't be the only one with this issue. I tried searching around the forums, but none of the fixes resolved my issue.

Thanks in advance!

Edit:

So I found the solution to me my notification sound and vibration issue. The latest update for Galaxy Wearable for my Gear S3 apparently now has an option to "Mute Connected Phone". I don't remember seeing this before. I guess this is on by default or it was set from the setting that I loaded from my Gear S3 backup, who knows. I do know that you will not get sound or vibration from notifications on your phone if it is on. I figured it out when my watch battery died and then a notification sounded on my phone. Of course all notification sounds and vibrations worked when my watch was disconnected. Once charged, I looked at the S3 notification settings and saw that one. Only took me a week. My phone is working, I will go back to my noob corporate job now.