I understand it is most likely an install issue with EGNX however I haven't done anything different than with all of the other sceneries. Any thoughts here?
As you can see from the screenshot you posted, the file searched by GSX is not there. You have a different version, with a name that ends with *TRM.BGL instead.
This might have happened because you had that file once, and now it's not there anymore for some reason, and maybe you changed/switched files when the sim was running, so GSX couldn't detect the change properly.
Try to force a cache rebuild, by removing the following folders:
%PROGRAMDATA%\Lockheed Martin\Prepar3d v3\SceneryIndexes
%PROGRAMDATA%\Virtuali\Couatl