此问题可能是由于通知渠道未正确设置导致的。在创建通知之前，请使用以下代码创建通知渠道：

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    // 设置通知渠道的ID、名称和描述
    String channelId = "my_channel_id";
    CharSequence channelName = "My Channel";
    String channelDescription = "Channel Description";
    int importance = NotificationManager.IMPORTANCE_HIGH;
    // 创建通知渠道
    NotificationChannel channel = new NotificationChannel(channelId, channelName, importance);
    channel.setDescription(channelDescription);
    // 注册通知渠道
    NotificationManager notificationManager = getSystemService(NotificationManager.class);
    notificationManager.createNotificationChannel(channel);
}

然后，在发送通知时，请确保已使用正确的通知渠道 ID：

String channelId = "my_channel_id";
NotificationCompat.Builder builder = new NotificationCompat.Builder(this, channelId)
    .setSmallIcon(R.drawable.ic_notification)
    .setContentTitle("My notification")
    .setContentText("Hello World!")
    .setPriority(NotificationCompat.PRIORITY_HIGH)
    .setAutoCancel(true);
NotificationManagerCompat notificationManager = NotificationManagerCompat.from(this);
notificationManager.notify(0, builder.build());