ROS2: topic subscribed but not received

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I have a device driver that publishes a Pointcloud2 message at 30 Hz.

I can subscribe the message in Rviz and I can see the correct pointcloud.

When I move the camera in 3D view the pointcloud disappears and I see Showing [0] points from [0] messages in Points under the Pointcloud Status.

If I open a console and I try to subscribe to the topic by command line using

$ ros2 topic echo /zed_node/point_cloud/cloud_registered

it seems that the message is not published indeed. I'm pretty sure that my node is publishing it because if I subscribe to it and remove the subscription I can see the total number of subscribers changing.

For further information I'm using Bouncy compiled from source under Ubuntu 16.04 and the following QOS settings:

    rmw_qos_profile_t depth_qos_profile = rmw_qos_profile_default; // Default QOS profile

    depth_qos_profile.durability = RMW_QOS_POLICY_DURABILITY_SYSTEM_DEFAULT;
    depth_qos_profile.history = RMW_QOS_POLICY_HISTORY_KEEP_LAST;
    depth_qos_profile.depth = 1;
    depth_qos_profile.reliability = RMW_QOS_POLICY_RELIABILITY_BEST_EFFORT;

Thank you for help

Walter