Stereo to mono problem

When converting a file from stereo to mono, Audition severely suppresses the amplitude of the entire file. [see photo: tinyurl -dot- com/46l96m ] This happens when using both the Convert Sample Rate method, as well as exporting a file from multi-track.

It gets weirder: files that were recorded quite a while back will process this conversion just fine, but newer ones will not. All files are recorded in 16-bit 44100 stereo and saved as a Windows PCM wav file - so as far as I can tell there is no difference and I'm simply confounded.

And weirder still: I've also tried doing the conversion on a separate computer and that also will not work - so I'm convinced it has something to do with the way the file was recorded or saved, but I have no idea what. Any help provided will get you into heaven, thanks.