When an object is a "Member of a Population" you cannot save the object, it throws "There was an error saving the file. Check the Errors and Warnings window for details.". Perhaps just omit the object population mode from the TGO/OBJ file handler?
Also, no warnings or errors are given with this error. Kinda just seems like a quirky bug than really any real reason it should give an error.
This could also be an avenue to expand upon the TGO file handler. It could load "Members of Populations" as a population within TG and save population settings (not the population itself).