Yes my 1520 is on denim. Bluetooth and wired headsets work just fine. Any direct microphone use with the handset, such as calls, video, note taking and Cortana type verbal input - the microphone does not work.
and as per my earlier post, I again changed out the microphone board (for the second time) and had the same results. Direct handset microphone worked for about a day. Then completely stopped. And when it was working, it was work perfectly. I even had the
"Hey Cortana" feature working.
now I need to check my update history to denim, because when I first got the phone prior to denim, I had the microphone issue only with calls. All other functions worked fine. Then at some point after the denim update, the microphone problem was prevalent
across the board.