It doesn't populate those folders, MODX does. All it does is visit each page with cURL, so it simulates a user visiting every page.
Does that folder get populated when you visit pages in the front end?
Is there anything in the error log?
Doesn't work for me anyway. Giveaway could be the fact it goes to 152%. Nothing gets populated in the folder so something is off. I use a Firefox add that opens all the links in my site at as an even cruder alternative. 150 open tabs...
