BeamNGVehicle::buildExportPolyList returns incorrect values

The function BeamNGVehicle::buildExportPolyList seems to be returning incorrect values/not returning all values for flexmesh parts of a vehicle. This bug can be reproduced by selecting a vehicle in the world editor and exporting it as a collada from the file menu. For example, when exporting a Gavril D-Series, the output looks like the following:


With just the vertices it looks like this:


Some propmeshes are coming through (not the wheels though in this example), and flexmesh geometry is incorrect.

It is likely BeamNGVehicle::buildExportPolyList causing these issues, since exporting colladas works for other SceneObject types.

Unfortunately, I haven't been able to find the root cause of the issue yet due to not knowing the exact structure of OptimizedPolyList and it therefore being very hard to parse through the disassembly.