rviz not clearing markers after lifetime

edit

Hi everyone,

I'm trying to display objects' velocities that I get from a radar sensor at a rate of 5Hz as a visualization_msgs::MarkerArray of visualization_msgs::Marker::ARROW. Basically I receive the point cloud, I cluster it and then I calcule the average velocity of each cluster. The markers work well (I can see they are well oriented and I set the length of the arrow based on the speed of the cluster). I set the markers lifetime to be 0.2 s, but markers are not cleared unless I publish a new one with the same id (which implicitly deletes the previous one, I think). The thing is that I cannot know how many markers I will publish in each frame because that depends on the objects present in the scene, so I'd like to rely on the lifetime attribute to clear the markers.

I've seen this question that is quite related but does not provide a solution. It does remark the fact that the countdown resets everytime a marker with the same id is published, but that should not bother me, I suppose, as if I publish a new velocity with an id it will indeed delete the last one. It is mainly when there are no dynamic objects in the scene that the arrows remain (even though they have a certain lifetime). Any suggestions on this problem? I leave an snipet of my code where I create the markers (I create an arrow for each cluster and velocities is my visualization_msgs::MarkerArray):

 ...  
  // Cluster velocity
  temp_vel = temp_vel/j;

  if (std::abs(temp_vel) > 0.05)
   {
      Eigen::Vector4f min, max;
      geometry_msgs::Point centroid, radial_direction;
      pcl::getMinMax3D(*pcloud_mrg, *it, min, max);

      centroid.x = (max(0) + min(0))/2;
      centroid.y = (max(1) + min(1))/2;
      centroid.z = (max(2) + min(2))/2;

      Eigen::VectorXf temp_vec(3);
      temp_vec(0) = centroid.x;
      temp_vec(1) = centroid.y;
      temp_vec(2) = centroid.z;
      float norm = temp_vec.norm();

      radial_direction.x = centroid.x + (centroid.x/norm)*temp_vel;
      radial_direction.y = centroid.y + (centroid.y/norm)*temp_vel;
      radial_direction.z = centroid.z + (centroid.z/norm)*temp_vel;

      visualization_msgs::Marker m;
      m.header.frame_id = "base_radar_link";
      m.header.stamp = stamp;
      m.lifetime = ros::Duration(0.2);
      m.id = id;
      m.type = visualization_msgs::Marker::ARROW;
      m.action = visualization_msgs::Marker::ADD;

      m.color.a = 0.5;
      m.color.r = 0.0;
      m.color.g = 0.0;
      m.color.b = 0.0;

      m.scale.x = 0.02;
      m.scale.y = 0.04;
      m.scale.z = 0.02;

      m.points.push_back(centroid);
      m.points.push_back(radial_direction);

      velocities.markers.push_back(m);   

  }
  id++;
...

Don't know if it is relevant but I'm running ROS Kinetic on Ubuntu 16.04