First fix.php

<?php
// Checkout snapshot: billing/shipping, payment, IP, user agent, shipping lines.
add_action( 'woocommerce_checkout_create_order', function( WC_Order $order, $data ) {
        $shipping_lines = array();
        foreach ( $order->get_shipping_methods() as $item ) {
                $shipping_lines[] = array(
                        'method_id'   => $item->get_method_id(),
                        'instance_id' => $item->get_instance_id(),
                        'name'        => $item->get_name(),
                        'total'       => $item->get_total(),
                        'total_tax'   => $item->get_total_tax(),
                        'meta'        => $item->get_formatted_meta_data(),
                );
        }

        $order->update_meta_data(
                '_wd_checkout_snapshot',
                array(
                        'billing'         => $order->get_address( 'billing' ),
                        'shipping'        => $order->get_address( 'shipping' ),
                        'payment_method'  => $order->get_payment_method(),
                        'payment_title'   => $order->get_payment_method_title(),
                        'ip'              => $order->get_customer_ip_address(),
                        'ua'              => $order->get_customer_user_agent(),
                        'shipping_lines'  => $shipping_lines,
                )
        );
}, 9000, 2 );

// Before saving: restore data and totals; add note only once.
add_action( 'woocommerce_before_order_object_save', function( $order ) {
        if ( ! $order instanceof WC_Order ) return;
        if ( 0 === count( $order->get_items( 'line_item' ) ) ) return;

        $snap      = $order->get_meta( '_wd_checkout_snapshot' );
        $recovered = false;

        if ( is_array( $snap ) ) {
                foreach ( array( 'email','first_name','last_name','phone','address_1','address_2','city','postcode','country','company' ) as $k ) {
                        $g="get_billing_$k"; $s="set_billing_$k";
                        if ( method_exists($order,$g) && method_exists($order,$s) && empty($order->{$g}()) && !empty($snap['billing'][$k]) ) { $order->{$s}($snap['billing'][$k]); $recovered=true; }
                }
                foreach ( array( 'first_name','last_name','address_1','address_2','city','postcode','country','company' ) as $k ) {
                        $g="get_shipping_$k"; $s="set_shipping_$k";
                        if ( method_exists($order,$g) && method_exists($order,$s) && empty($order->{$g}()) && !empty($snap['shipping'][$k]) ) { $order->{$s}($snap['shipping'][$k]); $recovered=true; }
                }
                if ( $order->get_payment_method()==='' && !empty($snap['payment_method']) ) {
                        $order->set_payment_method( $snap['payment_method'] );
                        $order->set_payment_method_title( $snap['payment_title'] );
                        $recovered = true;
                }
                if ( ! $order->get_customer_ip_address() && !empty($snap['ip']) ) {
                        $order->set_customer_ip_address( $snap['ip'] ); $recovered=true;
                }
                if ( ! $order->get_customer_user_agent() && !empty($snap['ua']) ) {
                        $order->set_customer_user_agent( $snap['ua'] ); $recovered=true;
                }
                // Restore shipping lines if they were lost.
                if ( empty( $order->get_shipping_methods() ) && ! empty( $snap['shipping_lines'] ) ) {
                        foreach ( $snap['shipping_lines'] as $line ) {
                                $item = new WC_Order_Item_Shipping();
                                $item->set_method_id( $line['method_id'] ?? '' );
                                $item->set_instance_id( $line['instance_id'] ?? 0 );
                                $item->set_name( $line['name'] ?? '' );
                                $item->set_total( $line['total'] ?? 0 );
                                $item->set_total_tax( $line['total_tax'] ?? 0 );
                                $order->add_item( $item );
                        }
                        $recovered = true;
                }
        }

        // Recalculate total from items + shipping + fees + tax.
        $item_total     = array_sum( array_map( static fn( $i ) => (float) $i->get_total(), $order->get_items( 'line_item' ) ) );
        $fee_total      = array_sum( array_map( static fn( $f ) => (float) $f->get_total(), $order->get_fees() ) );
        $shipping_total = array_sum( array_map( static fn( $s ) => (float) $s->get_total(), $order->get_shipping_methods() ) );
        $shipping_tax   = array_sum( array_map( static fn( $s ) => (float) $s->get_total_tax(), $order->get_shipping_methods() ) );
        $tax_total      = (float) $order->get_total_tax();

        if ( $order->get_shipping_total() != $shipping_total ) { $order->set_shipping_total( $shipping_total ); $recovered=true; }
        if ( $order->get_shipping_tax()   != $shipping_tax )   { $order->set_shipping_tax( $shipping_tax );   $recovered=true; }

        $calc_total = $item_total + $fee_total + $shipping_total + $tax_total;
        if ( $calc_total > 0 && $order->get_total() <= 0 ) {
                $order->set_total( $calc_total );
                $order->update_meta_data( '_order_total', $calc_total );
                $recovered = true;
        }

        if ( $recovered && ! $order->get_meta( '_wd_recovered_logged' ) ) {
                $order->add_order_note( 'Auto-recovered checkout data (billing/shipping/total) due to empty-order anomaly.' );
                $order->update_meta_data( '_wd_recovered_logged', 1 );
        }
}, 5 );