I have just uploaded the new stable release of ModelConverterX, version 1.7. The main changes compared to the previous stable release are:

• Much improved support to export FS2004 aircraft MDL files.
• Internal and external representation of aircraft are shown as two separate models. Especially useful for FS2004 aircraft where based on user variables one had to be selected before.
• A building generator wizard to easily make 3D buildings.
• Many improvements in the support of MSFS 2020.
• Command line interface to convert objects.
• Support for P3D v6.
• And many many small bug fixes and improvements.

I would suggest everybody who is using the stable release to update to this new version.