
The function only displays waveforms for each audio channel contained within the clip, but does not allow editing of the embedded individual channels separately.
Page 480 of the Manual:
“While a single averaged audio waveform representing all the channels in that clip is shown by default, you can switch any clip to seeing each individual waveform in a vertical stack by right-clicking any audio clip and choosing Display Individual Audio Channels.
Whenever you cut an audio clip, you cut all audio channels with it. Audio channels that are embedded within a single track cannot be individually edited.”