Hi Hugh.
In FMS Data Manager Settings make sure you have the latest version 1.8.14.0130. If not please download latest, from Navigraph, install and run.
In Settings, make sure your paths for X-Plan 12 and P3D v6 are correct. If not, correct these and press Save. In Addon Mappings delete all X-Plane 12, X-Plane 12 addon and P3D v6 entries, press Scan and Save.
In Addon List, select and Update X-Plane 12, X-Plane 12 addon and P3D v6 entries.
Cheers
Ian