BuddyPress.org

@clairem – perhaps the functions.php file of your custom theme needs to be updated to be compatible with the new Buddypress? I’m merely guessing because that is where you make your edits to bring most WP themes compatible with Buddypress. If it’s a premium theme the designer should be able to help you pretty quickly.

If not maybe try posting a screen shot so we can better understand if this is a css issue or something else (if you don’t want to share the URL).