I spent a few hours last week struggling with the Audio Punch-In Tool. I could not monitor the audio during record or preview.  I've used the tool many times over the years but this time I was stumped.  

I finally figured out that you must have at least one video track in the sequence in order for the existing audio tracks to be heard during punch-in.  Anyone know if it's always been this way, or can explain this functionality?

Thanks! Jack