Ahh, then recording to mono won't work for you. Sorry.
For the record you record to mono by setting to L&R, then record onto a track with the type set to Mono audio track.
RB will put left side on that ttrack, and right side on next available track.

This L/R edit feature you refer to did work at one point, I remember trying it.

I do not work here, but the benefits are still awesome
Make your sound your own!