scook
Keep in mind, you told SONAR where the synth output should go. You decided not to use the tracks. Then you told SONAR to freeze the synth. Now you want SONAR to remove empty waves after you instructed it to generate them. I suppose there could be another freeze option but it definitely would be a feature request. SONAR would have no idea in advance of freezing if there would be audio generated or if the empty tracks were created intentionally so the delete would happen after the freeze.
I work with project templates, which have a series of tracks that are standard and possibly will be used in the new project.
But I do not want the Synth (Kontakt) load all the instruments, consuming a large portion of RAM, while I'm in the middle of project development and while I do not need these tracks.
Therefore, the best option is to freeze the synth until it is needed to use it.
Remove the tracks or change your references is not a good option.
Having a giant Wav file and completely blank (dua Sonar limitation) is also not a good option.
In my opinion, it is not at all difficult Sonar interpret if a track does not contain data and does not generate a "dumb" file.