Last Updated field - Why?

I have been trying to update all the records in my database for a progress report.  We have over 700 records since January of 2013.  I was doing this, but decided it would be best to make a backup (compressed enlx file) and a copy (using the File → Save a copy… command) before I went any further. 

When I came in the next morning and reopened the newly copied library and the original library, the field I had been using to see whether I had updated a certain record, Last Updated, had all been changed to the previous day’s date.  The smart groups I had set up to determine which records needed updating were now useless.  Why did this happen, and what can I do now, did it have something to do with the copy?

If you want to designate a static date or other field you can customize a field across the reference types -but seems you’ll need to reset your setup to use the customized field. (Also note there’s no current option in EndNote X7 to change the Last Updated field.)


From the EndNote X7 Help topic:


The Auto Date Stamp Fields

Two Auto Date Stamp fields are available that you can add to the Library window.


The Added to Library and Last Updated date fields are inserted when you save a new reference. The Last Updated date is reset each time you save changes to a reference. The date format of the Auto Date Stamp fields matches your default operating system settings (for example, 4/16/2012).

To add the two Auto Date Stamp fields to the Library window, select Preferences > Display Fields. From the Field column, select the Added to Library and/or Last Updated fields. EndNote populates the Heading column with your selection.


You cannot edit, print, or export either of the Auto Date Stamp fields. You can, however, display and sort these fields from the Library window just as you can with any other EndNote field.

Note: For references entered with EndNote version X1 or earlier, the Added to Library field is left blank and the Last Updated field displays the date of conversion to EndNote.