Email are not being send when queue is processed laravel

I am trying to send notification email + database notification to multiple users. I am experiencing this strange behavior with laravel queue, it sends database notification perfectly but do not send email. And If I remove the queue it works just fine, both the database notification as well as email are being received.

Note: Queue gets processed successfully.

Laravel 7

QUEUE_CONNECTION=database

Notificaion:

<?php

namespace App\Notifications;

use Illuminate\Bus\Queueable;
use Illuminate\Contracts\Queue\ShouldQueue;
use Illuminate\Notifications\Messages\MailMessage;
use Illuminate\Notifications\Notification;

class CommentOnTask extends Notification implements ShouldQueue
{
    use Queueable;

    private $data;

    /**
     * Create a new notification instance.
     *
     * @return void
     */
    public function __construct($data)
    {
        $this->data = $data;
    }

    /**
     * Get the notification's delivery channels.
     *
     * @param  mixed  $notifiable
     * @return array
     */
    public function via($notifiable)
    {
        return ['database', 'mail'];
    }

    /**
     * Get the mail representation of the notification.
     *
     * @param  mixed  $notifiable
     * @return \Illuminate\Notifications\Messages\MailMessage
     */
    public function toMail($notifiable)
    {
        return (new MailMessage)
                    ->line('The introduction to the notification.')
                    ->action('Notification Action', url('/'))
                    ->line('Thank you for using our application!');
    }

    /**
     * Get the array representation of the notification.
     *
     * @param  mixed  $notifiable
     * @return array
     */
    public function toArray($notifiable)
    {
        return [
            //
        ];
    }

    /**
     * Get the database representation of the notification.
     *
     * @param  mixed  $notifiable
     * @return array
     */
    public function toDatabase($notifiable)
    {
        return [
            'body'       => $this->data['body'],
        ];
    }
}

Controller:

<?php
.
.
.
        $members = $task->users;
        $members = $members->merge($task->followers);

        Notification::send($members, new CommentOnTask($data));