All,
We found the problem and have fixed it. It has to do with one of the servers not responding correctly to the old code code in use. The new code has a .aspx extension instead of the old .pxf extension you're using. So on slight occassion when it hits that server, the thumbshots will not appear. We apologize for the inconvenience. Eventhough it's fixed, always update to the new code if and when you can. Thanks!