Hi there,
This is a bit harder to find with the new www.remarpro.com plugins directory layout (something I don’t have any control over) but there’s some information on customizing the series-toc page in the FAQ section:
In the organize-series folder you’ll see a file called seriestoc.php. It’s what gets loaded when you go to your series toc url (defaults at \series-toc\ but you can change this on the series options page). Chances are though it doesn’t look great with your theme (the file included just gives you an idea of what you can put in the file). What you want to do is copy this file to your theme folder and then modify it to match your theme structure (see your themes archive page for an example). You don’t need to put any of the WordPress loop code in this file.
It sounds like it may be something theme specific in your case.
