Certain audio tracks not rendering I'm not sure the best way to explain the scenario so I'll do my best, please don't hesitate to ask if I'm missing something obvious to help build the picture.

My problem is I've edited a video in Premiere (CS6) and when I export it part of the audio is missing and I cant seem to find any reason why.

The audio that is missing is at the start and end of the video, it's a stereo piece of music. The rest of the audio is mono (and renders out no problem). When I'm playing back the preview everything plays as expected, nothing seems to be muted or turned down. The settings on the export are set to match the quality of the music track that is missing. 

Any ideas why I can't get that audio to render? It's really frustrating! Cheers.

EDIT: I've tried rendering in different formats and sample rates. No joy.
Managed to dive in to it and root out the problem. Despite all the audio playing in the preview there was actually a channel solo'd in the audio mixer. I only noticed this when I ran an update on Premiere, de-authorised and re-authorised it (because of another issue that happened) the audio in the preview started to play back correctly as per the track solo status.

Thanks for those who looked at the question and tried to help.