For a couple years I used the built-in video capture tool in Windows 10 (press the windows key + G) and it would record Rocksmith just fine. Suddenly, a few months back it stopped working. 

Doesn't matter if Rocksmith has Exclusive Audio checked or not. Doesn't matter what settings I choose in the Windows Game Captuer Settings. Records the video without a sound. 

Drivers are up to date. 

Anybody experience this and find a fix for it?

I think either a Steam or Rocksmith update killed this for me. Which sucks because I upload recordings to YouTube.

Note, it will record other things just fine. I tested it on a Plex video I was watching and it worked perfectly. So far only Rocksmith is missing the audio. 

The solution was to edit the Rocksmith.ini file and change this line to read:

ForceDefaultPlaybackDevice=1