Vegas Pro will not properly render PCM audio in avi file on the timeline
I've been able to solve the issue recently with the following command in ffmpeg:

ffmpeg -i "input.avi" -c copy "output.mov"


I still have no understanding why Vegas would not work with the AVI. My system does this container rewrap at about 350x, so it's very fast. The only issue is if you have a ton of videos and you create a batch file, you should check your hard drive space before you try it.