I install all of my addons like one normally would into my community folders. My planes and plugins work perfectly fine, and when I finish the installation, my content manager tells me all of my airports and cities are registered and installed correctly. Whenever I attempt to load into a flight, I am stuck with default airports and scenery.
Asobo airports, on the other hand, work perfectly fine, I have not had a single issue with them. It seems to specifically be a third party issue.