MessageFilter ApproximateTime doesn't call callback function

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Hello, I'm trying to implement MessageFilter in a class. I'm using ROS1 Melodic on Ubuntu 18.04. The code compiles without any errors but when I play my bag file, the callback function aren't called. I checked some other questions but I couldn't find a solution. Here is my code :

Main:

#include <ros/ros.h>
#include "object_localization/CloudPainter.hpp"

int main(int argc, char** argv)
{
    ros::init(argc, argv, "cloud_painter");
    ros::NodeHandle node_handle("~");

    object_localization::CloudPainter cloud_painter(node_handle);

    ros::spin();
    return 0;
}

CloudPainter.hpp:

#pragma once

#include <ros/ros.h>

#include <message_filters/subscriber.h>
#include <message_filters/synchronizer.h>
#include <message_filters/sync_policies/approximate_time.h>

#include <sensor_msgs/PointCloud2.h>
#include <sensor_msgs/Image.h>

typedef message_filters::Subscriber<sensor_msgs::PointCloud2> PointCloudSubscriber;
typedef message_filters::Subscriber<sensor_msgs::Image> ImageSubscriber;
typedef message_filters::sync_policies::ApproximateTime<sensor_msgs::PointCloud2,
                                                        sensor_msgs::Image>
    MySyncPolicy;

namespace object_localization
{
class CloudPainter
{
public:
    CloudPainter(ros::NodeHandle& t_node_handle);

private:
    bool readParameters();

    void messageFilterCallback(const sensor_msgs::PointCloud2ConstPtr& t_point_cloud,
                    const sensor_msgs::ImageConstPtr& t_image);

    ros::NodeHandle& m_node_handle;
    std::string m_lidar_topic;
    std::string m_camera_topic;
    PointCloudSubscriber m_point_cloud_subscriber;
    ImageSubscriber m_image_subscriber;
    message_filters::Synchronizer<MySyncPolicy> m_synchronizer;
};
}  // namespace object_localization

CloudPainter.cpp:

#include "object_localization/CloudPainter.hpp"

namespace object_localization
{
CloudPainter::CloudPainter(ros::NodeHandle& t_node_handle)
: m_node_handle(t_node_handle)
, m_synchronizer(MySyncPolicy(10), m_point_cloud_subscriber, m_image_subscriber)
{
    if (!readParameters())
    {
        ROS_ERROR("Could not read parameters.");
        ros::requestShutdown();
    }

    ROS_INFO("Lidar topic: : %s", m_lidar_topic.c_str());
    ROS_INFO("Camera topic: : %s", m_camera_topic.c_str());

    m_point_cloud_subscriber.subscribe(m_node_handle, m_lidar_topic,  1);
    m_image_subscriber.subscribe(m_node_handle, m_camera_topic,  1);
    m_synchronizer.registerCallback(
        boost::bind(&CloudPainter::messageFilterCallback, this, _1, _2));

    ROS_INFO("Successfully launched node.");
}

bool CloudPainter::readParameters()
{
    if (!m_node_handle.getParam("lidar_topic", m_lidar_topic))
    {
        return false;
    }
    if (!m_node_handle.getParam("camera_topic", m_camera_topic))
    {
        return false;
    }
    return true;
}

void CloudPainter::messageFilterCallback(const sensor_msgs::PointCloud2ConstPtr& t_point_cloud,
                                        const sensor_msgs::ImageConstPtr& t_image)
{
    ROS_INFO("Callback.");
}
}  // namespace object_localization

Output:

[ INFO] [1625585829.773481527]: Lidar topic: : velodyne_points
[ INFO] [1625585829.774161339]: Camera topic: : pylon_camera_node/image_rect
[ INFO] [1625585829.777213271]: Successfully launched node.