I have been mixing down by selecting "bounce to tracks" and creating a new track.  I then apply Ozone 5 to that track and export the mix from that track.  Works well.
 
However, there have been comments recently about mixing down from the Master track.  I tried it by selecting all the individual tracks, applying Ozone 5 to the Master and then selecting the Master as the source to export audio.  However, that does not work as it reports "no audio".
 
I don't need to use the Master, but if it is supposed to work, what am I doing wrong?
 
 

As there has been some note elsewhere about what is the Master, when you talk about the Master is that a bus that feed your mains or the mains themselves.
 
I do a similar process to you in that I bounce all my tracks to a single track inside a project.  I assign the output of that track to feed my mains not my master bus, I then mute all the other tracks and place any additional processing I want in to the single tracks FX bin or Pro Channel.
 
Then when I want to export the track I select that track and export that track to wave.

To export the master, Go to Edit -> Select -> None. Then File -> Export -> Audio.
 
In the export dialog, pull up the "What You Hear" preset. Note that this will only do what you expect if you have all tracks output to a bus or Master, and all busses output to Master. In other words, if any track or bus bypasses the Master bus, I don't think it will be included.
 
Regards,
Dan
 

OK the "What you hear" works.  Thanks dcumpian.
 
I probably will never use it, but I wanted to know how to do it since it has been mentioned.