Super lame, as the easiest way for me - until now - to record rocksmith playthroughs has been shadowplay. I was having the same issue, where it would appear that recording was working in-game, but when I exited or alt-tabbed to look at my output directory it was empty. After searching the internets I only found this thread. Truly, the latest releases of gforce experience broken the ability to record rocksmith. I uninstalled gforce experience, and reinstalled an older version (v3.8.0.89) and it works again. I hope this is a bug and not 'working as intended', so that it is fixed in future releases of gforce exp.