Essential Sound for audio file (not multi-track)
There does not seem to be a way to use the Essential Sound panel in a waveform audio file--you are forced to first insert the file into a new multi-track file, use Essential Sound and then mix down. From a UX point of view there is no reason ES should not be available in waveform UI.
If this can't be implemented then minimally, I request that markers in the waveform file be preserved in the round trip.
Additionally, why not implement a tooltip that tells you ES is only available in multi-track?