Hi @jaedens
Please contact with Sponsors widget developer. this is not theme side issue. actually this plugin create own widget and area.
you have to put widgets in theme widget area.
register_sidebar( array(
'name' => __( 'Blog Sidebar', 'seopress' ),
'id' => 'sidebar-1',
'description' => __( 'Widgets for Blog sidebar. If you are using Full Width Layout in customize, then this sidebar will not display.', 'seopress' ),
'before_widget' => '<div id="%1$s" class="widget_sidebar_main clearfix %2$s">',
'after_widget' => '</div>',
'before_title' => '<h3 class="right-widget-title">',
'after_title' => '</h3>',
) );
You can see ‘widget_sidebar_main’ and ‘right-widget-title’. these are CSS selector and use to design widget. but your plugin generate different HTML/CSS.
Thanks