Hello to all
I having this issues for quite some time, all indications so far to seens to me that it is Whatsapp thats causing this issue. Not 100% sure, about that, but, most of the times this happened was just after I send someone a msg, I don?t hear the reply sound and when I going to check, I already know the problema ocurred, I got no sound when unlocking the screen, no typing sound, or any other sound, having this issues in the last 3 firmware updates, well since I got my Lumia 920.
My wife?s L720 got the same problem, she doens?t use as many app as I do, and I don?t have many apps my self, just some c?mera app, wheater, Official apps.
My friend Have a L630, he never had this issue, but he must have 3 or 4 apps installed, one of then Whats App.
So maybe a combination of Apps cause this.