Might be an issue with the CSV file, especially with line delimiters or encoding. How are you creating the CSV? We recommend using LibreOffice or OpenOffice. Or after teh file is created you can use Notepad++ to ensure that encoding is UTF-8 and EOL conversion is Unix Format.
Did you delete the last 30 records or the first 30? If it was the last 30, try deleting the first 30 and see how many it imports.