I have the same problem. I have the best sellers list module checked but it won't show up. I am running two different X-Cart installations on two servers where one of them is just a "dummy site" where I can experiment making changes without doing too much damage.
The other is the intended live site which I'm still working on. Here's the site:
The BS list doens't show up at all. THe dummy site does however...any ideas???
http://www.circuitcentral.com.au/shop/customer/