Repeated invisible notifications every 5 minutes

[FLrenwench]

Samsung Galaxy 10+ System UI 12

I timed it, it is ever 5 minutes and it is 1 second tone that sounds for an Amber Alert or emergency tone combined with vibration - it is not the normal chime.

I restarted phone, turned off all notification settings, put it in airplane mode (it still chimed), uninstalled numerous apps, took it out of its case.

This is every 5 minutes!

[AshP_]

This certainly sounds odd, @FLrenwench, do you have a charger connected to your S10+ when you hear this chime? Have you had a go at enabling Safe mode to see if the sound occurs? This temporarily disables third-party apps but leaves basic functions (calls, text, etc.) active to allow you to diagnose whether the issue is being caused by a third-party app. Here's a guide on enabling Safe mode: How to start my Galaxy phone or tablet in Safe Mode

[FLrenwench]

I started the phone in safe mode, it did not beep in Safe Mode

I deleted any apps downloaded over the weekend and restarted the phone in normal mode.

Then installed Avast for Mobile

It is still beeping every 5 minutes (yes I timed it).

The beep is not the normal alert chime, it vibrates first then there is a short sound like the beginning of an emergency announcement, then cuts off quickly.

[FLrenwench]

I just tried putting it in safe mode again - no beeps, but I have deleted any recent downloads and apps - this just started last night and it was only occasional, today it is at regular intervals of 5 minutes.

[sirjohneleth]

Check if you can install good lock app and the nice catch add on for it from galaxy store you can set this to track all sound vibrations etc and find where they come from.