Páginas de carrito y finalizar compra rotas. Errores en PHP log

No logro hacer funcionar el plugin, a pesar de probar diferentes variantes y combinaciones de configuración.

Problema: Las páginas en las que se aplica el plugin -carrito, finalizar compra- aparecen rotas. Numerosos errores en error-php.log.

Escenario: Sitio de prueba completamente limpio y sin plugins adicionales. Tienda con un solo producto, con peso y dimensiones. Configuración de plugin Andreani con usuario/contrase?a de prueba o producción y contratos de acuerdo a panel de control del cliente.
Wordpress 6.0.3
Woocommerce 7.0.0 (probé sin éxito rollback hasta ver 6.8.2)
Wanderlust Andreani para WooCommerce 2.0.201
Tema Storefront 4.1.3
PHP 8.0.12

En error-php.log:

[25-Oct-2022 11:34:02 UTC] PHP Warning:  session_start(): Session cannot be started after headers have already been sent in /home/c1991884/public_html/sbtest/wp-content/plugins/wanderlust-andreani-shipping/includes/class-wc-shipping-andreani.php on line 222
[25-Oct-2022 11:34:02 UTC] PHP Warning:  Undefined variable $andreani_weightb in /home/c1991884/public_html/sbtest/wp-content/plugins/wanderlust-andreani-shipping/includes/class-wc-shipping-andreani.php on line 248
[25-Oct-2022 11:34:02 UTC] PHP Warning:  Undefined variable $andreani_volumesy in /home/c1991884/public_html/sbtest/wp-content/plugins/wanderlust-andreani-shipping/includes/class-wc-shipping-andreani.php on line 250
[25-Oct-2022 11:34:03 UTC] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/c1991884/public_html/sbtest/wp-content/themes/storefront/header.php:10) in /home/c1991884/public_html/sbtest/wp-content/plugins/wanderlust-andreani-shipping/includes/class-wc-shipping-andreani.php on line 298
[25-Oct-2022 11:34:03 UTC] PHP Warning:  Attempt to read property "results" on null in /home/c1991884/public_html/sbtest/wp-content/plugins/wanderlust-andreani-shipping/includes/class-wc-shipping-andreani.php on line 312
[25-Oct-2022 11:34:03 UTC] PHP Fatal error:  Uncaught TypeError: Unsupported operand types: string * null in /home/c1991884/public_html/sbtest/wp-content/plugins/wanderlust-andreani-shipping/includes/class-wc-shipping-andreani.php:312
Stack trace:
#0 /path-original/sbtest/wp-content/plugins/woocommerce/includes/abstracts/abstract-wc-shipping-method.php(233): WC_Shipping_Andreani->calculate_shipping(Array)
#1 /path-original/sbtest/wp-content/plugins/woocommerce/includes/class-wc-shipping.php(348): WC_Shipping_Method->get_rates_for_package(Array)
#2 /path-original/sbtest/wp-content/plugins/woocommerce/includes/class-wc-shipping.php(260): WC_Shipping->calculate_shipping_for_package(Array, 0)
#3 /path-original/sbtest/wp-content/plugins/woocommerce/includes/class-wc-cart.php(1420): WC_Shipping->calculate_shipping(Array)
#4 /path-original/sbtest/wp-content/plugins/woocommerce/includes/class-wc-cart-totals.php(339): WC_Cart->calculate_shipping()
#5 /path-original/sbtest/wp-content/plugins/woocommerce/includes/class-wc-cart-totals.php(850): WC_Cart_Totals->get_shipping_from_cart()
#6 /path-original/sbtest/wp-content/plugins/woocommerce/includes/class-wc-cart-totals.php(144): WC_Cart_Totals->calculate_shipping_totals()
#7 /path-original/sbtest/wp-content/plugins/woocommerce/includes/class-wc-cart-totals.php(134): WC_Cart_Totals->calculate()
#8 /path-original/sbtest/wp-content/plugins/woocommerce/includes/class-wc-cart.php(1398): WC_Cart_Totals->__construct(Object(WC_Cart))
#9 /path-original/sbtest/wp-content/plugins/woocommerce/includes/shortcodes/class-wc-shortcode-cart.php(94): WC_Cart->calculate_totals()
#10 /path-original/sbtest/wp-content/plugins/woocommerce/includes/class-wc-shortcodes.php(72): WC_Shortcode_Cart::output(Array)
#11 /path-original/sbtest/wp-content/plugins/woocommerce/includes/class-wc-shortcodes.php(85): WC_Shortcodes::shortcode_wrapper(Array)
#12 /path-original/sbtest/wp-includes/shortcodes.php(356): WC_Shortcodes::cart('', '', 'woocommerce_car...')
#13 [internal function]: do_shortcode_tag(Array)
#14 /path-original/sbtest/wp-includes/shortcodes.php(228): preg_replace_callback('/\\[(\\[?)(woocom...', 'do_shortcode_ta...', '[woocommerce_ca...')
#15 /path-original/sbtest/wp-includes/class-wp-hook.php(307): do_shortcode('[woocommerce_ca...')
#16 /path-original/sbtest/wp-includes/plugin.php(191): WP_Hook->apply_filters('[woocommerce_ca...', Array)
#17 /path-original/sbtest/wp-includes/post-template.php(253): apply_filters('the_content', '<!-- wp:shortco...')
#18 /path-original/sbtest/wp-content/themes/storefront/inc/storefront-template-functions.php(352): the_content()
#19 /path-original/sbtest/wp-includes/class-wp-hook.php(307): storefront_page_content('')
#20 /path-original/sbtest/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters(NULL, Array)
#21 /path-original/sbtest/wp-includes/plugin.php(476): WP_Hook->do_action(Array)
#22 /path-original/sbtest/wp-content/themes/storefront/content-page.php(18): do_action('storefront_page')
#23 /path-original/sbtest/wp-includes/template.php(772): require('/home/c1991884/...')
#24 /path-original/sbtest/wp-includes/template.php(716): load_template('/home/c1991884/...', false, Array)
#25 /path-original/sbtest/wp-includes/general-template.php(204): locate_template(Array, true, false, Array)
#26 /path-original/sbtest/wp-content/themes/storefront/page.php(24): get_template_part('content', 'page')
#27 /path-original/sbtest/wp-includes/template-loader.php(106): include('/home/c1991884/...')
#28 /path-original/sbtest/wp-blog-header.php(19): require_once('/home/c1991884/...')
#29 /path-original/sbtest/index.php(17): require('/home/c1991884/...')
#30 {main}
  thrown in /path-original/sbtest/wp-content/plugins/wanderlust-andreani-shipping/includes/class-wc-shipping-andreani.php on line 312