It is post clip envelopes. The blog says post mute, but somehow mute is effective on the clip after Melodyne has processed it, not just before. Putting mute on a clip
before inserting Melodyne causes Melodyne to do its analysis on a silent clip. Then turning off mute still leaves it silent. Putting mute on
after applying Melodyne seems to work OK, namely muting and unmuting are both effective. What doesn't work is applying a clip envelope after Melodyne's analysis. And a clip envelope put on before Melodyne's analysis makes the envelope disappear and it's no longer editable.