When you render and export a composition from After Effects that does not have audio content, do you ever enable audio output intentionally (thus creating an empty audio track in the output file)?
If so, why, and what formats do you use?
We're in the process of making some improvements to how audio is handled, and we want to make sure that we haven't broken any common workflows.
(Note: If you're not sure about how to enable audio output, see this page: "FAQ: Why is there no sound (audio) in my output file?" )