Do you maybe know what can cause the problem?
It's likely a similar issue discussed here, with LH Simulation LHBP:
http://www.fsdreamteam.com/forum/index.php/topic,10797.msg83735.html#msg83735This scenery uses a similar method of creating lights as ground objects, to they must be protected from being removed by GSX (which removes all ground objects from a parking when you select it).
Is there a demo of this scenery I can download ?
As an alternative, do you know where they store their Simobjects ? They might have used the Simobject\Misc folder or create a new folder, to contain some folder with a folder name that should be easy to recognize to belong to that scenery. If you could post the SIM.CFG contained there, we could add a code pattern to protect their objects in GSX.