This seems to be a memory problem. Vue needs at least 8 to 10 minutes (or even more) to save such a heavy scene on your machine. You may think that Vue has finished saving because nothing seems to happen, the slider at bottom is on its end since a while and then you interrupt the program. That's wrong. Wait, wait, wait until it has finished. You can see when a saving is finished, if you can move the slider in the world browser again.