I'm having this same issue right now. I set 3 alarms, 6:00, 6:20, and 6:40 to go off every weekday. The past 2 days none of them have worked. I do not have DND on, and all volumes are maxed (ringtone, media, notifications, and system). This morning I opened the clock app, went to alarms, opened each of them and tried changing the alarm tone. Usually when tapping on a tone in the list it plays the sound, this morning it did not. Then I went to youTube to test the media sound. I received an error for each video I opened because the sound wasn't working. I was still receiving haptic feedback and sounds when typing, so the system sounds were still working, just not the media. I restarted the phone and it worked again, so I went back into the alarms and tried playing the tones again and it broke all media sounds again. Could it be an issue with the clock app or more specifically, the alarms?? Either way, this needs to be fixed ASAP!