At first I thought your problem would be that the end(s) of the threaded rod are damaged and do not start into the nut. That is easily fixed by grinding or filing the first thread or two, to remove the damaged part. I have never seen a bolt or a threaded rod like you describe. I wonder how they would be able to make one. If Scamp
people have one like that, they might have more. They might send you a replacement, but if you have to pay for shipping, you are better off going to a hardware store and get a replacement. That kind of hardware is not expensive. Good luck.