This is a PHP settings limitation, that affects some of our plugins.
The issue is because, on your web server, you have active a PHP limitation that prevents our plugin from saving more rules in it’s settings.
To fix this, you should update your PHP.ini file on your server (hosting) – from CPanel.
You should replace this line:
max_input_vars = 1000
with this one:
max_input_vars = 99999
If you don’t know how to do this, please contact your hosting support, they will help you edit the file and solve this issue.
You can also use this free plugin, to edit the php.ini file: https://ro.wordpress.org/plugins/php-settings/
After the file is updated, the plugin will be able to add more importing rules.
In some cases however, the hosting company does not allow the modification of the php.ini file. In this case, please send me an email to my email address: kisded@yahoo.com and I will try to help in another way.