Brief.
We have issued a patch of the 'admin_table_users.php' file after release 3.3 has been issued.
 
Description.
Now it is possible to export empty values for both affiliate_code and friendly_url fields.
 
Solution.
Please download an updated version of the file from here:
http://www.viart.com/downloads/admin_table_users-3.3.zip
Then extract the 'admin_table_users.php' file into the admin/ folder of your shop replacing an existing one. Don't forget to make a backup copy of the current file in case something goes wrong.