We've just installed a version of Joomla IP which supports Joomla version 3.4.8.
But the URL with the secret URL key for our IP address returns a page with "404 Article Not Found" instead of logging us into to the member's area of the website.
Sorry, I can't help you.
If you can reproduce this issue with the latest version of IP Login on an up-to-date Joomla 3 setup, I am happy to look into this.