Attachment Control Does Not Save File to List Item
When attaching a file to the Attachment control, the file does not attach correctly and the option to attach more files is not available.
From the list ribbon, go to the Nintex Forms Designer and check to make sure the rules used in the Nintex Form are valid. Calculated value controls or Nintex Form rules with invalid formulas will need to be fixed. Once the formulas used are valid, the Attachment control will work correctly.