Although Ken may have acqiuired and installed MSFS, AFAIK, his primary focus at this time is still on the FSX / P3D version(s) of FS.
IIUC, as Ken states
"when I exported the entire terminal buildings in MCX as a DAE file and imported it into Sketchup
...I infer that some 3D models in the multi-object scene may have been imported from default FS2Kx or 3rd party BGLs.
I would also infer that such BGL sources also contain placement info, such as the default OBX*.BGL
Thus, I would expect even (1) 3D model having been imported as a part of that aggregate multi-object scene have been oriented and placed properly relative to NSEW.
But since Ken may have MSFS installed, one might wonder if at the time he installed a recent DevRel of MCX, if/when MCX was (auto- ?) configured, an option was set to:
* MSFS as the "Preferred" FS version
...and thus to also:
* Correct 3D object placement by -180
IIUC, this latter setting is to work around the MSFS' arbitrary internal 3D model orientation that switches an axis to the opposite orientation of all prior FS versions.
The possible fix in this scenario, is for Ken to set these MCX Options
* FSX as Preferred version
* Disable -180 Heading orientation "correction"
...for ongoing use with FSX / P3D.
See MCX Manual PDF file
6.3 Object placement editor
The object placement editor allows you to place the selected object at a specific location and also
to view all locations that the object has already been placed at
, see 6.4.
specifies which axis is used as the upwards axis of the model. Not all importers
support this setting.
•Rotate 180 degrees specifies that the object should automatically be rotated 180 degrees
along the Z axis on import.
specifies the preferred FS version as used by ModelConverterX. This
preferred version influences from where textures and effect files are read, but it also influences
the format in which GUIDs are displayed.
However, it is possible if MCX exported in a 3D model exchange format for which Ken used either a default or non-default Sketchup plugin Ruby script importer, an axis got flipped.
IIRC, all the Sketchup importers I have used (and recommended to Ken) have had a prompt that halts the import until a reply is entered for any axis change option.
Ken might wish to keep a closer watch on all options available in either a default or 3rd party 3D model importer for Sketchup, and set them for a targeted FS version.
While it is easy enough to select all imported objects > Group > rotate on Z-axis in Sketchup, I would check MCX' Options to set them for (current) FS version use.
: For related info on Sketchup 3D model Axes and Cardinal Geographic Axes, see:
Some info on "handed-ness" and orientation of 3D model axes in FS2Kx and Sketchup:
Regarding MCX and Sketchup display of 3D model Axis orientation / handed-ness: