I have tried several times to Update GSX and GSX L2 to the latest version (3.06?) through the UNIVERSAL INSTALLER but it is only installing version 2.9.8. I have also tried using the live update exe that comes with GSX with the same result.
You are confusing GSX Pro ( the MSFS version ) with GSX/GSX L2. Latest version for P3D is 2.9.8, but when you use the Live Update to update it, it will bring the GSX *code* to the latest version, which won't be listed anywhere, since the GSX code is not a standard executable and FSX/P3D don't have a manifest file like MSFS, so we have no way to show the version.
But if you run the Live Update, and it doesn't download anything else, you HAVE the latest version-