Can’t save a variable Gift Card

Hi, I’m trying to create a gift card product with the Advanced Gift Card plugin. When I try to create a variable product, the first variation works but throws a 500 error, the subsequent ones will not work and all throw the same error :

{
    "error": {
        "type": 1,
        "file": "/srv/htdocs/wp-content/plugins/advanced-gift-cards-for-woocommerce/Objects/Product_Variable.php",
        "line": 57
    },
    "remote-logging": true,
    "backtrace": [
        "",
        "#0 /wordpress/plugins/google-listings-and-ads/2.9.2/src/Product/SyncerHooks.php(236): AGCFW\Objects\Product_Variable->get_available_variations('objects')",
        "#1 /wordpress/plugins/google-listings-and-ads/2.9.2/src/Product/SyncerHooks.php(162): Automattic\WooCommerce\GoogleListingsAndAds\Product\SyncerHooks->handle_update_products(Array)",
        "#2 /wordpress/core/6.7.1/wp-includes/class-wp-hook.php(324): Automattic\WooCommerce\GoogleListingsAndAds\Product\SyncerHooks->update_by_object(14312, Object(AGCFW\Objects\Product_Variable))",
        "#3 /wordpress/core/6.7.1/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(NULL, Array)",
        "#4 /wordpress/core/6.7.1/wp-includes/plugin.php(517): WP_Hook->do_action(Array)",
        "#5 /wordpress/plugins/woocommerce/9.4.3/includes/data-stores/class-wc-product-data-store-cpt.php(378): do_action('woocommerce_upd...', 14312, Object(AGCFW\Objects\Product_Variable))",
        "#6 /wordpress/plugins/woocommerce/9.4.3/includes/class-wc-data-store.php(196): WC_Product_Data_Store_CPT->update(Object(AGCFW\Objects\Product_Variable))",
        "#7 /wordpress/plugins/woocommerce/9.4.3/includes/abstracts/abstract-wc-product.php(1467): WC_Data_Store->update(Object(AGCFW\Objects\Product_Variable))",
        "#8 /wordpress/plugins/woocommerce/9.4.3/includes/admin/meta-boxes/class-wc-meta-box-product-data.php(454): WC_Product->save()",
        "#9 /wordpress/plugins/woocommerce/9.4.3/includes/class-wc-ajax.php(2438): WC_Meta_Box_Product_Data::save_variations(14312, Object(WP_Post))",
        "#10 /wordpress/core/6.7.1/wp-includes/class-wp-hook.php(324): WC_AJAX::save_variations('')",
        "#11 /wordpress/core/6.7.1/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters('', Array)",
        "#12 /wordpress/core/6.7.1/wp-includes/plugin.php(517): WP_Hook->do_action(Array)",
        "#13 /wordpress/core/6.7.1/wp-admin/admin-ajax.php(192): do_action('wp_ajax_woocomm...')",
        "#14 {main}",
        "thrown"
    ]
}

The page I need help with: [log in to see the link]