Hi…,
In FMS Data Manager Settings, check you have the latest version:
If not download and install from FMS Data Manager
Also in Settings, check you have the correct path for X-Plane 12, press Save.
In Addon Mappings tab select and Remove any X-Plane 12 and X-Plane 12 entries, press Scan and Save.
In Addon List, select and Update X-Plane 12 and X-Plane 12 entries.
Cheers
Ian