0. Make sure the track intereleave button is set to Stereo not Mono!!!
1. Set pan to CENTER (!!!!)
2. In the VIEW, OPTIONS, TRACKS, CLIPS, MIDI, REGION FX pull-downs, select TRACKS
3. Select "Bounce to Tracks"
4. Set "Source Category" to Tracks. The name of the stereo track you are converting should be shown.
5. Set "Channel Format" to "Split Mono"
6. Set "Dithering" to "None"
7. Uncheck all the boxes except "64-bit Engine" and "Fast Bounce" [as mettelus said]
8. Hit OK