Waveform disappears when zoom-editing in X3e.

Greetings All,
When attempting to De-Ess a vocal track in X3e, I have waveform issues.
 
This happened in earlier versions (8.5, X1) but went away briefly in X2's iterations.
 
When I zoom in to see the offending "S", "T" or "F" high frequency sibilant, I can highlight and reduce its gain just fine,
but then that edited section of the waveform flat-lines (disappears), and the remaining waveform "stretches" so that I no longer know where I'm at.
 
I can press [ALT]-Z and zoom back out, and the waveform looks fine.
 
It's the zoom-in, zoom-out that is troublesome.
It'd be nice to stay zoomed in to perform the edits for a track.
 
I've tried bouncing the clip, but that's too much bouncing after every sibilant.
I've also tried deleting and optimizing the picture cache, as well as recomputing the picture via the clip's Associated Audio Files.

Nothing works.
 
(Fader automation is not an option - I prefer to manually de-ess.)
 
Has anyone encountered this, and is there a fix?
 
For the duration of this project, I think I'll port the track out to RX Advanced for spectral editing of these sibilants, as I can knock out a track faster there than fighting with Sonar.
 
Thanks for any and all ideas.
 
Cheers,
MG