I upgraded to the Editor, so cannot test what you are seeing; then came across the link below in another thread (Melodyne's site about ARA and X3), which basically says that the Melodyne export to MIDI is not included in the Essential version. Based on this, I believe the functionality you are seeing is the ARA/X3's Audio to MIDI conversion. I have not used this much at all, so hopefully someone who has can chime in.
http://helpcenter.celemony.com/editor2/en/singeltrack_daw_sonar.html?q=MIDI%20Export "MIDI export Even with ARA, a command is provided in the “Settings” menu of Melodyne editor and Melodyne assistant (
but not Melodyne essential) for the exporting of MIDI. But ARA makes exporting MIDI to a Sonar track far simpler: if you have previously opened a clip in Melodyne, all you need to do is drag it by its upper handle to a MIDI or instrument track within your Sonar arrangement. Note that the polyphonic conversion of audio to MIDI is only possible with Melodyne editor or the trial version when activated. Otherwise the conversion of audio to MIDI is always monophonic, and also functions in Melodyne’s playback mode.
Tip:
it is not, in fact, necessary to create a Region FX with Melodyne in order to convert audio to MIDI. It suffices to drag it to a MIDI or instrument track in the manner already described. The requisite exchange of information with Melodyne is performed by Sonar in the background using the ARA protocol."
The only other "quick test" may be to remove the FX region and drag and drop the clean audio track into a MIDI track and see if you get the same result.