Hello again and sorry for the late reply!
What you are describing sounds like an incorrect path to the X-Plane directory in the FMS Data Manager. Kindly uninstall your current version of the application and download the latest from your Navigraph Account page.
Upon reinstalling the application, please make sure that the path to X-Plane is indeed correct! See FAQ - Installing Navdata AIRAC Updates for reference.
Best regards,
Malte