Wow, I knew it was a firmware update and it would work with a dock, but I don't have a dock.Ignore, it is NOT a hardware issue
It is a "problem" (but not really a problem) introduced with the January and later firmwares. It goes away if you plug the device into a dock and will come back if no dock is used. It has absolutely no effect on the system
Prior to this audio went out via mDP to my monitor's speakers, and to TV when I used mDP-to-HDMI cable to a TV. Since the January firmware update I get no sound to my monitor or TV connecting to the mDP.You really never said if you were having trouble with hearing any audio. Were you just looking in Device Manager and noticed the one baseball bat? If the audio is going to your speakers OK than I wouldn't worry about it.