Laravel Excel - Mapping Doesn't Bring Any Data (Doesn't Work)

Hello forks! I am using the Laravel Excel package to export a list of transactions with the relationships. In the example below, I have used two methods ('headings' and 'map'). When I export, I receive the data for headings but no data for mapping. Please help me, folks. Thank you so much in advance.

Export / TransactionsExport.php

<?php

namespace App\Exports;

use App\Models\Transaction;
use Maatwebsite\Excel\Concerns\WithMapping;
use Maatwebsite\Excel\Concerns\WithHeadings;

class TransactionsExport implements WithHeadings, WithMapping
{
    /**
    * @var Transaction $transaction
    */
    public function map($transaction): array
    {
        dd('work?');
        return [
            $transaction->invoice_no,
            $transaction->tenant->name,
            $transaction->end_date,
        ];
    }

    public function headings(): array
    {
        return [
            'Invoice No.',
            'Tenant Name',
            'End Date',
        ];
    }
}

TransactionController.php

use App\Exports\TransactionsExport;

// Export as excel
    public function export() {
        return Excel::download(new TransactionsExport, 'transactions.xlsx');
    }