How to do multitrack mixdown of mono files

Hi,

When attempting to export multitrack mixdowns I'm unable to select for mono files. I've tried to change the files to mono in the 'convert sample type' window in the export multitrack mixdown tool but it always reverts to stereo.  I've tried to work around this in multiple ways but I'm still getting all stereo files.   What am I missing?  Most DAW's have quick ways of making multitrack bounces of mono tracks, as it's something you do often if you want to move your sessions to different DAW's/studios for mixing. Whats up with Audition?  Any help is appreciated.