by Davo Smith.
The 'draft' file records are not cleaned up until a week or so after they were used (so that a user who messes around with a form for a while won't find their 'draft' files have been deleted whilst they weren't looking).
You still need to see if the 'real' file is stored somewhere (with component = 'mod_assignment'). If it isn't, then either you didn't click 'save' on the feedback form, or the version of Moodle you are using has a bug in the 'save feedback' code (which may well have been fixed in more recent versions of Moodle).