I used to have a stereo-audio-mono-mic headset that connected to my Lumia 925 with a three-ring'd 3.5mm cable. When using it, sometimes, the audio would stop being stereo and it would only output on the left ear. Restarting the phone would make the problem go away.
I then bought a Lumia 640 Dual sim LTE and didn't have the above problem. Until one day, with a set of Bose QC20 stereo-audio-mono-mic headset, I could only hear audio from the left ear bud. Restarting the phone does nothing.
I have tried a non-mic headphone and the audio works in stereo. But my QC20 is still on left-ear only.
In my debugging I have noticed the following: - The surround sound option is enabled when I plug in QC20, but - after a flicker - turns itself off and becomes disabled when audio starts to play. However, with the normal headphones it stays enabled and on. Having the surround sound option off before playing audio does not alter things. - The QC20 work fine (both buds) on a laptop or Samsung android phone. - The QC20 are the non-apple variety and used to work with my phone. Since they worked, No phone update occurred. - Lumia 640 is running stock WP8.1 update 2. - The QC20 mic works when making calls. - I've cleaned the headphone hole with an ear bud.
To me, it's as if the phone is failing to recognise that it has stereo and mic, and thinks it's mono and mic combo. I've cleaned the
My only next thing to try is to do a hardreset (restore to factory settings), and if that fails, a WP recovery.
What may be the problem? What are my options, aside restore/recovery? Is it a common problem?