I now have the answer for the crash. The second export is defective. It exports facets referencing vertices not exported. I'm not surprised the OBJ importer in VWD crashes as it's not supposed to happen. Any script developper can reproduce the error. Using silent OBJ export and import examples from the Daz doc center, You can try to export a mesh, import it back and export again the imported mesh, all in a sequence in the same script.

If you think you can help, I've no qualm sending you the sources. I just have to warn you that some of the code is dynamically generated by translating Python into javascript and executed afterwards, so debugging is not always simple. But the import and export code are in the script (and they are mostly cut and paste from Daz examples).