I've checked updates for x-plane 11 with x-plane 11 installer version 126.96.36.199 (update x-plane option). The program found no updates and finishes. When I read log.txt I've noticed at the en of file sentences beginning with "deleting ... Custom Scenery/Aerosoft - LFPG Paris CDG/" and all of its subfolders. I checked that folder and I see the scenery no longer exists.
I re-run the installer but this time I chose "update scenery on-line" option and the missing scenery is recovered from the server.
I don't understand why the installer erases it the first time.