Could you look and send us the Pulse logs? Go to Settings > Extend and Logs (view or export/download) and message them and we can take a look.
It might be that the RW blog is not formatted in a great way to be compatible. It’s not an invalid feed, just perhaps not the way we are looking for it. RSS is tricky and Tumblr, WP and a few others import fine.
An option could be to take your XML RSS feed and run it through something like Google Feedburner to “cleanse” it and then try it on the importer. Also add more pages in the importer settings…but the logs should tell us what is happening.