The project I'm trying to mix down doesn't begin until about 14 seconds into the timeline for the project. I utilized the Project>Set Timecode At Now command to zero the timecode right where the project's audio begins, yet when I execute the Export Audio command, the resulting file contains all that 'dead air' for the first 14 seconds.
What am I doing wrong/what else do I need to do to eliminate that first 14 seconds of the project's file?
Thanks!

Select the portion to be exported in the timeline (+ the tracks in question). That is, if you for some reason can not delete the "unnecessary" 14 seconds.
 
I think that timecode thing is only for syncing with video (but I'm not sure).

Duplicate

Thank you - yes that worked. Simply highlight on the timeline the section you want mixed down.