The plot thickens! I was asked some time ago by HiFi to install a simconnect.msi file on both my server and remote. Examination of the properties gave this version and it matched my EZCA equivalent.
That's likely the issue: they gave you an FSX version to install into P3D, which shouldn't usually a problem, other than being a tell tale these add-on are not using any of P3D-specific features, and they are 32 bit as well but, again, this shouldn't be a problem as such ( GSX is of course a fully native 64 bit program using the native 64 bit P3D Simconnect ) but, the problem might be having all these different copies of it, some of them spread in multiple folders.
That's not how Simconnect should be installed, a normal installation of the FSX 32 bit version Simconnect client should be in the Windows\WinSxS folders, with more than one folder if you have various versions of the FSX Simconnect ( RTM, SP1 or SP2 ), and they are not just "copied" there, there's a fairly complex registration process involved which is done by the .MSI installer, which makes the WinSxS method working, which should ( WHEN IT WORKS ) allow multiple versions of the same .DLL to be loaded in memory and running at the same time, depending which add-on requires which version. It's a bit of memory wasting, but when it works ( which sometimes it doesn't ), it works.
However, all those multiple copies of the Simconnect.DLL spread around outside the Windows\WinSxS folder, might confuse the WinSxS system, which expect them to be in the folder they were registered into by the .MSI installer, and might cause the sim to be "stuck" with the FSX version of the Simconnect, resulting in only add-ons using the FSX version working, and causing issues to "native" add-ons like GSX, which require the P3D version and the WinSxS system not being messed with.
In fact, the WinSxS is so complex that almost nobody, not even Microsoft, seem to be able to troubleshoot it when something's doesn't work. Which explains why both Microsoft itself ( they used it in older VC++ redistributables, but abandoned it in more recent versions ) but also Lockheed Martin got rid of the WinSxS method, and reverted to static linking for P3D, which IS a bit of memory waste but, considering with 64 bit this is not really a problem, and in FSX the memory was wasted in any case, because some add-ons used the RTM version, some the SP1, some the SP2 version, they decided it was best to stop using it.
However, if you still have add-ons using the FSX Simconnect, you are at risk of the WinSxS ( Side by side loading ) quirks, which are almost impossible to troubleshoot correctly.
I'd start by removing each and every copy of Simconnect which is not native P3D native, at least remove it from all places where is not supposed to be, that is outside the Windows\WinSxS folder.