Parallel import

Good afternoon! I was checking the parallel import for the possibility of inclusion and encountered problems.
With these settings of the importer:
modelImporter.materialImportMode = ModelImporterMaterialImportMode.ImportStandard;
modelImporter.materialLocation = ModelImporterMaterialLocation.External;
modelImporter.materialName = ModelImporterMaterialName.BasedOnMaterialName;
modelImporter.materialSearch = ModelImporterMaterialSearch.Everywhere;

As long as parallel import is turned off, everything works fine. But when I turn on parallel import, the importer remap what it finds, but for materials that it has not found it cannot create folders and materials and the import crashes.
I see that for parallel it is written that it should not create resources. But then how and what is the purpose of parallel import if native functions cannot be executed in it. Like create a folder and a material?
Okay, I see that the parallel import asks to enable embedded materials. I enable embedded materials, but then the remapper stops working!
Well the embedded materials themselves look like a very strange feature, such materials are quite difficult to work with.