More than likely the import utility did not look for new "importuserid" field in vBulletin user table during import. The script may have to be edited to reflect.
| Altering tables |
ImpEx will now Alter the tables in the vB database to include import id numbers.This is needed during the import process for maintaining references between the tables during an import.They will also be left after the import if you need to link back to the original vB userid.
I am thinking that the script should be fixed before running vs. repair the import.