I started downloading and a few entries appeared in the "sets" folder correctly rewritten. Then they stopped. I paused the download and copied one of the URLs which didn't get rewritten, I pasted it into the TEST field in the URL rewrites and it produced the correct result, yet it didn't get rewritten and saved as part of the download.
With id=118, 271, 1042 the URL's were rewritten and saved correctly, whilst 1043, 1048, 296 were not.
There seems to be no logic to this so I can only assume this is a bug as it happended in the latest version 6.x, and also after I upgraded to version 7.
Can you please send me the Project settings and access to the site to reproduce this and fix?
You may send it for me to email@example.com. Select the Project, press Ctrl+C on keyboard and paste to the E-mail.