Same here, seems the priblem is latest Sony Sociallife update.
Try the following: clear cache and data, uninstall updates, deactivate app, restart. Let me know.
Well, what I did was have someone call me, and call answering was sent to external speaker as usual. During the conversation, I plugged in the headphones and call went to headphones, and then, during the call, I removed them.
After that, I had another three incoming calls, and everything went back to normal, calls were directed to internal audio, not external.
I did that, because I remember that two days ago I was using Walkman app, headphones on, and phone rang. Answered the call from phone's dialler app, and all was fine. And since then, it all started with calls to external, like the phone did not "remember" that headphones were removed.
But that is just my guess, since it seems this plugging/unplugging headphones now fixed it. But you also might be right, since it's two days ago that I've updated Socialife app indeed.
I will keep monitoring incoming calls' behavior, and if it reverts back to external, I will unistall updates, and clear cache etc.
Oh, and before doing the headphones trick, just plain restarting the phone didn't work.
Let me know if you can pinpoint more exactly the cause of all this.
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