FCM notifications not delivered to all devices using laravel-notification-channels/fcm

I'm using the laravel-notification-channels/fcm package to send notifications to all devices, but despite logs showing messages sent, the devices never receive any notifications.

I have a DeviceToken model/table (DeviceToken.php) that stores all the device fcm_tokens:

PHPCopied
<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Notifications\Notifiable;

class DeviceToken extends Model
{
    use Notifiable;

    protected $fillable = ['fcm_token'];

    public static function getAllTokens(): array
    {
        return self::pluck('fcm_token')->toArray();
    }
}

I also created a notification that should broadcast to all devices whenever a new entry is created in a notifications table. Below is the SendNotification notification class (SendNotification.php):

PHPCopied
<?php

namespace App\Notifications;

use Illuminate\Bus\Queueable;
use Illuminate\Contracts\Queue\ShouldQueue;
use Illuminate\Notifications\Notification;
use NotificationChannels\Fcm\FcmChannel;
use NotificationChannels\Fcm\FcmMessage;
use NotificationChannels\Fcm\Resources\Notification as FcmNotification;

class SendNotification extends Notification
{
    public $title;
    public $body;

    /**
     * Create a new notification instance.
     */
    public function __construct($title, $body)
    {
        $this->title = $title;
        $this->body = $body;
    }

    public function via($notifiable)
    {
        return [FcmChannel::class];
    }

    /**
     * Get the FCM representation of the notification.
     */
    public function toFcm($notifiable): FcmMessage
    {
        return (new FcmMessage(notification: new FcmNotification(
            title: $this->title,
            body: $this->body
        )))
            ->data(['data1' => 'value', 'data2' => 'value2'])  // Additional data
            ->custom([
                'android' => [
                    'notification' => [
                        'color' => '#0A0A0A',
                    ],
                ],
                'apns' => [
                    'fcm_options' => [
                        'analytics_label' => 'analytics',
                    ],
                ],
            ]);
    }
}

Additionally, I have an observer (NotificationObserver.php) that is triggered whenever a new notification record is created:

PHPCopied
<?php

namespace App\Observers;

use App\Models\DeviceToken;
use App\Models\Notification;
use App\Notifications\SendNotification;
use Illuminate\Contracts\Events\ShouldHandleEventsAfterCommit;
use Illuminate\Support\Facades\Log;
use Illuminate\Support\Facades\Notification as NotificationFacade;
use NotificationChannels\Fcm\FcmChannel;

class NotificationObserver implements ShouldHandleEventsAfterCommit
{
    /**
     * Handle the Notification "created" event.
     */
    public function created(Notification $notification): void
    {
        // Fetch all FCM tokens from the device_tokens table
        $deviceTokens = DeviceToken::getAllTokens();

        if (!empty($deviceTokens)) {
            // Send the notification via FCM
            try {
                // Optionally, chunk the tokens if you have many (e.g., 1000)
                $chunkSize = 500;
                $chunks = array_chunk($deviceTokens, $chunkSize);

                foreach ($chunks as $chunk) {
                    NotificationFacade::route(FcmChannel::class, $chunk)
                        ->notify(new SendNotification($notification->title, $notification->body));
                }

                Log::channel("notification")->info("Notification sent to " . count($deviceTokens) . " devices.");
            } catch (\Exception $e) {
                Log::channel("notification")->error("Error sending notification: " . $e->getMessage());
            }
        } else {
            Log::channel("notification")->warning("No device tokens found");
        }
    }
}

According to the logs, notifications are supposedly sent (e.g., "Notification sent to 3 devices."), but no device actually receives the notification. I've already tried troubleshooting common issues without success.

Any help or suggestions to resolve this would be greatly appreciated.