This bug happen when you are listening any song and the currently one finish, then the next song should start but the volume goes to 0% or its mute, I don't know exactly what happen but you can hear nothing while you can see how song timer is passing.
The only solution I have find us to move the timer button to another second of the song manually or change song with previous or next button for listen music again at app or lock screen widget.
It happens randomly (aprox 3/4 of the times) and only when the phone changes song automatically.
I checked it with phone speakers, with Bluetooth and with USB-C cable and that bug happens on that 3 ways.
