I have a surface pro 3, with Skype 184.108.40.206 installed on Windows 8.1. When in calls, I can hear received audio, but my microphone will only give static or nothing. I have checked in the settings and the surface's microphone is selected, and I have tried to reinstall Skype several times.
The microphone is working fine in other applications, such as Google Hangouts or the Sound recorder. I have also tried the web based version of skype and it still does not work, and I have also tried adjusting the levels of the microphone to no avail. Skype did work with the original Metro skype that came with the machine, but hasn't worked with Skype for Windows (desktop).
I do not see any optional updates specifically marked for audio in Windows update (but there are ~200 with "Update for Windows 8.1 (KB #)").