Nodelet zero-copy doesn't seem to work, source and destination addresses don't match

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As the title says, I am trying to essentially "prove" that zero copy between nodelets works and I'm having trouble. I've got a ZeroCopyTestSenderNodelet as follows:

#include "ros/ros.h"
#include "nodelet/nodelet.h"
#include <pluginlib/class_list_macros.h>
#include <std_msgs/Int32.h>
namespace ros_test_package
{
    class ZeroCopyTestSenderNodelet : public nodelet::Nodelet
    {
    public:
        inline virtual void onInit()
        {
            NODELET_INFO("[ZeroCopyTestSender]\tInitializing...");
            count_ = 0;
            getPrivateNodeHandle().param("rate", rate_, double(0.5));
            pub_ = getNodeHandle().advertise<std_msgs::Int32>("test_int", 1);
            pub_loop_ = getNodeHandle().createTimer(ros::Duration(1.0f/rate_), boost::bind(&ZeroCopyTestSenderNodelet::pubLoopFunc, this, _1));
            NODELET_INFO("[ZeroCopyTestSender]\tInitialized.");
        };
        inline void pubLoopFunc(const ros::TimerEvent& event)
        {
            std_msgs::Int32 this_int_msg;
            this_int_msg.data = count_++;
            NODELET_INFO("[ZeroCopyTestSender]\t--> value %d, address 0x%08X...", this_int_msg.data, &(this_int_msg.data));
            pub_.publish(this_int_msg);
            ros::spinOnce();
        }
    private:
        ros::Publisher pub_;
        ros::Timer pub_loop_;
        double rate_;
        int count_;
    };
} // namespace ros_test_package
PLUGINLIB_EXPORT_CLASS(ros_test_package::ZeroCopyTestSenderNodelet, nodelet::Nodelet)

and a ZeroCopyTestReceiverNodelet as follows:

#include "ros/ros.h"
#include "nodelet/nodelet.h"
#include <pluginlib/class_list_macros.h>
#include <std_msgs/Int32.h>
namespace ros_test_package
{
    class ZeroCopyTestReceiverNodelet : public nodelet::Nodelet
    {
    public:
        inline virtual void onInit()
        {
            NODELET_INFO("[ZeroCopyTestReceiver]\tInitializing...");
            sub_ = getNodeHandle().subscribe("test_int", 1, &ZeroCopyTestReceiverNodelet::callback, this);
            NODELET_INFO("[ZeroCopyTestReceiver]\tInitialized.");
        };
        inline void callback(const std_msgs::Int32ConstPtr test_int_msg)
        {
            NODELET_INFO("[ZeroCopyTestReceiver]\t<-- value %d, address 0x%08X.", test_int_msg->data, &(test_int_msg->data));
        }
    private:
        ros::Subscriber sub_;
    };
} // namespace ros_test_package
PLUGINLIB_EXPORT_CLASS(ros_test_package::ZeroCopyTestReceiverNodelet, nodelet::Nodelet)

I am launching a sender and two receivers on the same manager using the following:

<launch>
    <node pkg="nodelet" type="nodelet" name="zero_copy_test_manager" args="manager" output="screen"/>
    <node pkg="nodelet" type="nodelet" name="zero_copy_test_sender_nodelet" args="load ros_test_package/ZeroCopyTestSenderNodelet zero_copy_test_manager" output="screen"/>
    <node pkg="nodelet" type="nodelet" name="zero_copy_test_receiver_nodelet" args="load ros_test_package/ZeroCopyTestReceiverNodelet zero_copy_test_manager" output="screen"/>
    <node pkg="nodelet" type="nodelet" name="zero_copy_test_receiver_nodelet2" args="load ros_test_package/ZeroCopyTestReceiverNodelet zero_copy_test_manager" output="screen"/>
</launch>

The output of running this is as follows, and is similar regardless if there is only 1 or 2 receivers launched:

[/zero_copy_test_manager@1610252429.626189985] Initializing nodelet with 12 worker threads.
[/zero_copy_test_manager@1610252429.635256318] [ZeroCopyTestSender] Initializing...
[/zero_copy_test_manager@1610252429.638284332] [ZeroCopyTestSender] Initialized.
[/zero_copy_test_manager@1610252429.649166515] [ZeroCopyTestReceiver]   Initializing...
[/zero_copy_test_manager@1610252429.655558553] [ZeroCopyTestReceiver]   Initialized.
[/zero_copy_test_manager@1610252429.659189946] [ZeroCopyTestReceiver]   Initializing...
[/zero_copy_test_manager@1610252429.663768935] [ZeroCopyTestReceiver]   Initialized.
[/zero_copy_test_manager@1610252431.639207762] [ZeroCopyTestSender] --> value 0, address 0x0CF8E46C...
[/zero_copy_test_manager@1610252431.640040360] [ZeroCopyTestReceiver]   <-- value 0, address 0xE40017CC.
[/zero_copy_test_manager@1610252431.640214038] [ZeroCopyTestReceiver]   <-- value 0, address 0xE40017CC.
[/zero_copy_test_manager@1610252433.639092537] [ZeroCopyTestSender] --> value 1, address 0x0CF8E46C...
[/zero_copy_test_manager@1610252433.639549131] [ZeroCopyTestReceiver]   <-- value 1, address 0xE40017CC.
[/zero_copy_test_manager@1610252433.639722691] [ZeroCopyTestReceiver]   <-- value 1, address 0xE40017CC.
[/zero_copy_test_manager@1610252435.638775083] [ZeroCopyTestSender] --> value 2, address 0x0CF8E46C...
[/zero_copy_test_manager@1610252435.639248751] [ZeroCopyTestReceiver]   <-- value 2, address 0xE400182C.
[/zero_copy_test_manager@1610252435.639409818] [ZeroCopyTestReceiver]   <-- value 2, address 0xE400182C.
[/zero_copy_test_manager@1610252437.638406888] [ZeroCopyTestSender] --> value 3, address 0x0CF8E46C...
[/zero_copy_test_manager@1610252437.638697812] [ZeroCopyTestReceiver]   <-- value 3, address 0xE400182C.
[/zero_copy_test_manager@1610252437.638795855] [ZeroCopyTestReceiver]   <-- value 3, address 0xE400182C.
[/zero_copy_test_manager@1610252439.639133032] [ZeroCopyTestSender] --> value 4, address 0x0CF8E46C...
[/zero_copy_test_manager@1610252439.639587543] [ZeroCopyTestReceiver]   <-- value 4, address 0xD800151C.
[/zero_copy_test_manager@1610252439.639744379] [ZeroCopyTestReceiver]   <-- value 4, address 0xD800151C.
[/zero_copy_test_manager@1610252441.638872904] [ZeroCopyTestSender] --> value 5, address 0x0CF8E46C...
[/zero_copy_test_manager@1610252441.639297394] [ZeroCopyTestReceiver]   < ...