I am using Windows Movie Maker 2012 on Windows 7. I typically use it to record videos via the webcam, edit those videos, and save them as edited WMVs. I've been doing this for several years now. Typically the audio waveforms show up in the right hand section of the screen where the editing takes place. 

Out of nowhere, they disappeared. I have tried opening the same files which previously showed waveforms, nothing. No matter how much I expand the footage, nothing is there. 

Is there a setting somewhere? 

I have tried reinstalling. Still no wave forms.