Hi Derek, thanks for your interest in this.
I opened one of my later session files and scanned through my user corrections to find any instances that would help. It didn't take long to find one but I've discovered that the size of the correction makes a difference as to whether it can be split up. I use the narrow corrections by default, and when I set a correction at minimum width, the stereo selection doesn't appear to work. Interestingly, if I then resize the correction to a larger size, the trace will disappear indicating the correction has been removed from that channel. I played around with this a little while and tried to break the programme but was unable to.
I'd say in 99% of all cases where channel separation might be desirable, the resulting distortion is negligible. That said, I have experienced instances where a correction misapplied to a channel has caused
noise in that channel, often where the waveform is uniform and symetrical. I can't immediately recall where these have occurred (and finding one now could possibly take hours or even days), but the next time I come across one I'll send it to you.