I tried the update right now with P3D (not that I wasn't sure it works, but you never know...), and it updates correctly the correct version of the files, with no errors.
If the updated tries to update using the old Live Update server, it because you main GSX installation is old, so your updater itself is old too. Or, you have a mix-match between old/new files, so you are running an old updater over a new installation.
Download and install the latest Stand-Alone Addon Manager, or the latest GSX full installer, which should update everything, even the updater.