New PubMed (NIH).enf strips 'PMC' from the PMC number

The new filter EndNote puts out strips the prefix “PMC” from the PMC number when being imported. This is not listed as an edit when I go to “Field Editing” for Custom 2 in the edit filter window.  We need to keep the prefix “PMC” on those numbers.  Can someone tell me where else that can be down so I can undo it, or can EndNote update the filter NOT to remove the prefix “PMC”?