Man, I'll throw a party the day I install an FSDreamteam scenery that actually works on first try.
They always work on the first try. When they don't, it's ALWAYS a problem caused by something else. Usually flight sim files corrupted by other addons or conflicts caused by other addons.
There's no difference whatsoever in how the different sceneries are installed. The installer it's exactly the same, the installation method is exactly the same, and they all use the add-on.xml method, which is the way a P3D scenery is supposed to be installed natively.
No buildings are showing, only a double ground photo - one bellow ground level and another above, with mesh issues. Tried Orbx vector utility to disable airport elevation correction.
You are having two problems at the same time here. The "no buildings" issue it's caused because the scenery is not found in the Scenery Library, everything else it's caused by OrbX.
It's NOT enough to run just the AEC tool (which I'm not even sure it has been updated to recognize sceneries installed with the add-on.xml method), you must also install the OrbX fix found on the OrbX forum, which solves the issue they caused at KLAS.
All the while, KMEM and KIAH are working ok.
If those two are working, you should just forget *everything* about antivirus, software, modules, etc. If they work, it's clear that all FSDT software is installed correctly.
If the Addon Manager says that some sceneries cannot be found in the scenery library, the most common reason for this is the simplest one: when trying to fix something that wasn't a problem of our installers to begin with, maybe you uninstalled, reinstalled the Addon Manager, and forgot to reinstall the SCENERY.
If you uninstalled (not needed, of course) the scenery, be sure you also reinstalled it.
After the installation, you are supposed to see the scenery listed as an Addon in the "Options->ADDON" menu (which is NOT the "Addons" menu), and in the Scenery Library GRAYED OUT. This is normal, and indicates that scenery has been installed from an add-on.xml, not in the scenery.cfg.
Another common reason why you don't see the scenery, is if you tried to "fix" the problem by adding the scenery to the Scenery Library manually. This should NOT be done, because doing this, you caused a conflict of the scenery conflicting with itself, which will result in no scenery showing up. If you added the scenery manually, remove it, and restart the sim.
The scenery should be listed only ONCE, and MUST be GRAYED out in the Scenery Library.