The most Recent Firmware 5.18.6 FIXED this jailbreak. So make sure you have a Firmware older than that and stop the device from updating!
Fill up the Space of the Kindle and Block autoupdates with the Hotfix. You can check if your Autoupdates are blocked with the "UpdateBlock Status" App from Kindleforge (Custom App Store)
If your Kindle is already on a newer version it's recommended to just fill up the entire device anyways to make future Updates impossible so that you don't accidentally get yet another jailbreak fix update when a new jailbreak releases