If a mailing list is created using the Drupal backend, you can subscribe people to the list, but if you go to the subscribers page there is no pager, unlike with the MLM backends. I've not found a lot of time to look into this one, but it seems to only be an issue with the Drupal backend. This makes it difficult to manipulate subscriptions past the first page. Have tried this with multiple themes -- I don't think it's a theming issue --