rqt_joint_trajectory_controller crashes when selection controller manager

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Whlist $ roscore and $ roslaunch kuka_rsi_hw_interface test_hardware_interface.launch sim:=false are running, I run $ rosrun rqt_joint_trajectory_controller rqt_joint_trajectory_controller and the interface appears. However, the moment I select '/controller_manager' in the 'controller manager ns' drop-down menu, it freezes and I have to force-quit.

My launch file looks like this:

<?xml version="1.0" encoding="utf-8"?>

<launch> <arg name="sim" default="true"/>

<rosparam file="$(find kuka_rsi_hw_interface)/test/test_params_sim.yaml" command="load" if="$(arg sim)"/>
<rosparam file="$(find kuka_rsi_hw_interface)/test/test_params.yaml" command="load" unless="$(arg sim)"/>

<param name="robot_description" command="$(find xacro)/xacro.py '$(find kuka_kr150_support)/urdf/kr150_2.xacro'"/>
<!-- Start node without FT sensor -->
<node name="kuka_hardware_interface" pkg="kuka_rsi_hw_interface"
  type="kuka_hardware_interface_node" respawn="false"
  output="screen"
  required="true"/>

<!-- Load joint controller configurations from YAML file to parameter server -->
<rosparam file="$(find kuka_rsi_hw_interface)/config/hardware_controllers.yaml" command="load"/>
<!-- Load standard kuka controller joint names from YAML file to parameter server -->
<rosparam file="$(find kuka_rsi_hw_interface)/config/controller_joint_names.yaml" command="load"/>

<!-- Load controllers -->
<node name="controller_spawner" pkg="controller_manager" type="spawner" respawn="false" output="screen"
    args="position_trajectory_controller joint_state_controller --shutdown-timeout 1"/>
<!-- Load robot state publisher -->
<node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" />

<!-- Load RSI simulation node -->
<node name='kuka_rsi_simulator' pkg='kuka_rsi_simulator' type="kuka_rsi_simulator" args="127.0.0.1 49152" if="$(arg sim)" />

</launch>