PHP Fatal error since 3.1.x series

Since updating to the 3.1 series we are seeing this error in the PHP logs. It is also causing the dashboard to not load completely as the javascript is unresponsive and the side menu options don’t pop out. There is a 500 error in the browser console in this case but it doesn’t list a specific file it just points to /wp-admin.

PHP Fatal error:  Uncaught TypeError: {closure}(): Argument #1 ($content) must be of type string, null given, called in /home/user/public_html/wp-includes/class-wp-hook.php on line 308 and defined in /home/user/public_html/wp-content/plugins/kadence-blocks/includes/advanced-form/advanced-form-cpt.php:1629
Stack trace:
#0 /home/user/public_html/wp-includes/class-wp-hook.php(308): {closure}(NULL, Object(WP_Post))
#1 /home/user/public_html/wp-includes/plugin.php(205): WP_Hook->apply_filters(NULL, Array)
#2 /home/user/public_html/wp-admin/includes/post.php(762): apply_filters('default_content', '', Object(WP_Post))
#3 /home/user/public_html/wp-admin/includes/dashboard.php(557): get_default_post_to_edit('post', true)
#4 /home/user/public_html/wp-admin/includes/template.php(1445): wp_dashboard_quick_press('', Array)
#5 /home/user/public_html/wp-admin/includes/dashboard.php(274): do_meta_boxes(Object(WP_Screen), 'side', '')
#6 /home/user/public_html/wp-admin/index.php(203): wp_dashboard()
#7 {main}
  thrown in /home/user/public_html/wp-content/plugins/kadence-blocks/includes/advanced-form/advanced-form-cpt.php on line 1629