Hi Tic:
I agree with Dave's assessment of this scenario, as it is unlikely OrbX would ever place that type of scenery to load from within [FS install path]\Scenery\World Scenery.
At most, one would see airport stubs used for Altitude adjustments etc., but AFAIK, not RWYs.
Here's an edited excerpt from one of my old posts on the FTX Central "Insertion Point" option for OrbX scenery layers in Scenery Library:
By default,
FTX Central utility always re-inserts
FTX layers to a position at- / near the top of-
P3D Scenery Library GUI stack of layers.
By default, when the
FTX Central configuration utility runs
automatically following installation /configuration of OrbX FTX scenery packages:
* Custom entries are added to the 'active'
Terrain.Cfg if they are not already present.
* Several OrbX FTX scenery Area layers are added to the 'top' position of the 'active' FS
Scenery Library GUI stack of layers.
Because by default, OrbX FTX scenery Area layers are added to the 'top' position of the
P3D Scenery Library GUI, custom scenery may not render properly (if at all), so one should allow for non-OrbX add-on or personally-created custom scenery to be loaded
later by placing them
above the OrbX FTX scenery Area layers ...at- or nearer to- the '
top' position of the FS Scenery Library GUI.
Each time OrbX
FTX Central utility is run OrbX FTX scenery Area layers are again automatically added to the 'top' position of the 'active' FS
Scenery Library GUI stack of layers by default.
One can change that default behavior of OrbX FTX Central utility by configuring the OrbX FTX scenery Area layers to be automatically placed at a
lower position in the 'active' FS
Scenery Library GUI stack of layers by:
OrbX FTX Central Menu > Tools > Scenery Library Configuration >
FTX Scenery Library Insertion Points
NOTE: Newer versions of OrbX
FTX Central utility may be subject to a different menu / dialog configurations
This results in an assigned position, above which OrbX FTX scenery Area layers will
NOT be inserted ...until a new
Insertion Point is assigned within that
FTX Central utility dialog.
PS: Other considerations may include Alpha-numeric file name contention between the BGL(s) containing the RWY objects from both yourself and OrbX, as well as how your add-on implemented transparency, as in some cases, scenery objects may be 'bleed-through to the top' ...from layers
below one's own in the Scenery Library.
Hope this info helps with the troubleshooting process.
GaryGB