I have experienced the same for Telegram and gmail notifications too. No sound alert and screen doesn't turn on, but as soon as I press the power button to turn the screen on, message tone is heard and all the notifications bubbles keep popping up one after another.
I have experienced the same for Telegram and gmail notifications too. No sound alert and screen doesn't turn on, but as soon as I press the power button to turn the screen on, message tone is heard and all the notifications bubbles keep popping up one after another.