Ah thanks for the link and sorry that I have forgotten it …
I would try following steps:
- close your sim
- delete your
content.xmlfile (I guess you know where this file is located - when not, you will find the answer here
) - start the sim and look in the Marketplace - all airport should be visible
- close the sim again
- start the Navigraph Navdata Center (please be sure you have installed the latest version - v1.0.8)
- install the new cycle
- close the Navigraph Navdata Center and start the sim again
- check the Marketplace again, if all airports are still visible - should be
When not … hmm 
… but thinking positive 
Good luck and let us know the result please
Thank you very much,
Richard