Hi all,
I had the same issue with my work notebook (HP Elitebook) and none of the previous solutions worked for me. I only was able to connect to 'stereo' and not to 'Hands-Free AG Audio'. I only have the microphone with the latter one.
I asked my IT support and they told me to do a battery reset. I had to detach the charger and all adapters from my notebook (especially the charger!) and then press the power button for 50 sec. After restarting the notebook my microphone worked again. I haven't expected Auch an easy solution but it worked out for me.
I hope this helps you!
Best regards
Alex