What is the source of the sound?
Just now, my phone was sounding an alarm or something. I searched for a minute or maybe longer, but I couldn't find the source of the alarm. It didn't respond to volume down or up. It didn't come from the clock app. I restarted my phone just to shut it up. I don't know if this was a bug or not. It would be useful to have a bell icon in the notification area when an app is making sound. I don't know if it is something easy to implement or not. Just an idea. It would have helped me just now.
This bug also occurred with my device. The alarm is triggered as soon as a new version of the messenger "Signal" is released. I used the official apk file from the website.
As with the OP I could not find the alarm source directly at first and had to restart the device. On closer examination I noticed that as soon as the alarm goes on, a small dialog appears at the top of the screen for a few seconds. The dialog notifies that a new version of Signal is available. After a few seconds the dialog disappears, but the alarm continues.
I think the alarm also appeared in silent mode. I'm not sure, though.
Device: Xperia XA2 Plus - Dual SIM
Systematics ( 2020-04-15 11:24:08 +0200 )editjust a side note: please try to use title and tags in a way they reflect the topic.
rozgwi ( 2020-04-15 14:46:00 +0200 )editIt isn't only Signal. I've had the Signal alarm, but I also had an alarm from to-doist every other day at 9.00 AM. It took more than a week to find out it was to-doist. My phone is 95% of the time in silent mode. I can confirm the alarm sounds in silent mode.
ThijssjihT ( 2020-05-06 13:25:42 +0200 )edit