error after update

Hello, after updating to the latest version 1.3.6.1, a php error is thrown at the woocommerce track order page:

Fatal error: Uncaught Error: Call to undefined function trackship_admin_customizer()
in /home/***/public_html/wp-content/plugins/trackship-for-woocommerce/includes/class-wc-trackship-front.php on line 284

Call stack:

    WC_TrackShip_Front::display_tracking_page()
    wp-content/plugins/trackship-for-woocommerce/includes/class-wc-trackship-front.php:104
    WC_TrackShip_Front::show_tracking_page_widget()
    wp-includes/class-wp-hook.php:307
    WP_Hook::apply_filters()
    wp-includes/class-wp-hook.php:331
    WP_Hook::do_action()
    wp-includes/plugin.php:474
    do_action()
    wp-content/plugins/woocommerce/templates/order/tracking.php:60
    include()
    wp-content/plugins/woocommerce/includes/wc-core-functions.php:345
    wc_get_template()
    wp-content/plugins/woocommerce/includes/shortcodes/class-wc-shortcode-order-tracking.php:59
    WC_Shortcode_Order_Tracking::output()
    wp-content/plugins/woocommerce/includes/class-wc-shortcodes.php:72
    WC_Shortcodes::shortcode_wrapper()
    wp-content/plugins/woocommerce/includes/class-wc-shortcodes.php:105
    WC_Shortcodes::order_tracking()
    wp-includes/shortcodes.php:356