Fatal error when changing status to delivered

Getting a fatal error upon clicking delivered status. Email is also not being sent to customer.

Error message:
Fatal error: Uncaught Error: Call to undefined method WC_Advanced_Shipment_Tracking_Email_Manager::email_content() in /home/customer/www/xxxxx.com/public_html/wp-content/plugins/woo-advanced-shipment-tracking/includes/emails/class-shipment-delivered-email.php:147 Stack trace: #0 /home/customer/www/xxxxx.com/public_html/wp-content/plugins/woocommerce/includes/emails/class-wc-email.php(541): WC_Email_Customer_Delivered_Order->get_content_html() #1 /home/customer/www/xxxxx.com/public_html/wp-content/plugins/woo-advanced-shipment-tracking/includes/customizer/class-wc-email-customizer.php(499): WC_Email->get_content() #2 /home/customer/www/xxxxx.com/public_html/wp-content/plugins/woo-advanced-shipment-tracking/includes/customizer/preview/delivered_preview.php(20): wcast_initialise_customizer_email->preview_delivered_email() #3 /home/customer/www/xxxxx.com/public_html/wp-content/plugins/woo-advanced-shipment-tracking/includes/customizer/class-wc-email-customizer.php(440): include(‘/home/customer/…’) # in /home/customer/www/xxxxx.com/public_html/wp-content/plugins/woo-advanced-shipment-tracking/includes/emails/class-shipment-delivered-email.php on line 147
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