The record you have shown from the database is for the 'draft' file, not the file in its final location.
In Moodle, when you open up a form that has files within it (either in the HTML editor or via a file upload box), all the existing files are copied into a 'draft' area. When you submit the form, the Moodle code should copy all the files back into the 'real' file area. It works this way so that you can press 'cancel', instead of submitting the form and your original files will still be as they were before you started editing the form.
Is there a record in the database that matches the file in its final / real location?
The 'component' field should be 'mod_assignment' (I'd have to look up in the code to find out what the 'filearea' field should be).
If that record is not found, then, for some reason, the files are not being copied across when you click 'save feedback'.
You might want to see if updating to Moodle 2.2.11 (the last version in the 2.2 branch) fixes the problem (or even jumping up to a currently supported version of Moodle like 2.5/2.6).