I looked in my archive record of installs and found an installation executable for GSX. I uninstalled my current GSX (everything) and executed this older downloaded file thinking beyond hope that some friendly gremlin might just take pity on me and I was in luck. I now have all the necessaries to run GSX.
The old GSX required the VC++ 2005 runtimes, and installed them automatically. The current version don't, because they require the VC++ 2013 runtimes instead.
However, they are still required by Simconnect *itself* so, even if GSX doesn't require the VC++ 2005 runtimes, if Simconnect doesn't work (because of the missing runtimes), GSX won't work too.
However, the VC++ 2005 runtimes included with the old GSX installer that apparently "fixed" your problem, where exactly the same you were supposed to download and install yourself from the Microsoft site in the #2 solution of the above thread which indicates all the know solutions to the problem of missing menu items so, I really cannot explain why the problem was fixed by installing the old GSX installer, and not by installing the same runtimes manually.
Usually, it's exactly the opposite: installing manually should be more reliable than having them launched from the installer.