Same issue here (2.0.0.10 Saimaa). To activate audio in all Android apps, the only workaround in my knowledge is launching my provider's mobile TV app (Proximus TVeverywhere). No audio by default, but disabling then re-enabling sound within the app restores normal audio.

Apparently, any Android app having audio disable/enable option can do it. TVeverywhere is the only one I have installed with that option.