GLTF 3D exporter UI app not working with mod vehicles?

Is the "GLTF 3D exporter" UI app supposed to only work with vanilla vehicles, or is this a bug?

I tried exporting several official BeamNG vehicles (D-series, H-series, Covet), and they all exported succesfully; resulting in a ~4 MB .GLB file.

I also tried exporting an official vehicle with mod parts on it (Ibishu pigeon with the wings/tail/propeller from the "Fligeon - The Flying Pigeon" mod), and that also exported succesfully as a ~3.7 MB .GLB file.

However, when I try exporting any mod vehicle (regardless of whether it's an Automation export like the "1955 Cutler-Randall Conquistador" or a mod that was manually made by someone like the "Capsule") it either doesn't export anything at all, leaving just an empty folder in documents\beamng.drive\0.24\vehicles\vehiclename, or it only exports a 1 KB .GLB file that does not work and gives the error "Failed opening gltf file: Too short data size for glTF Binary".

Why does this happen, and is there anything that can be done against it?

edit: I also tried doing the same thing in safe mode, with only the vehicle mod I'm trying to export active, but the results where still the same.

edit 2: I asked my friend to try it on his computer as well, and it had the exact same results (vanilla vehicles do export, vanilla vehicles with mod parts do export, completely new mod cars don't export) as it had with me. Therefore I don't think it's an issue with my computer or my BeamNG installation, but rather a bug in BeamNG itself.