PyDrake: Meshcat Not Visualzing URDF with (psuedo) Spherical Joint

Question

I am trying to add reaction wheels to a robotic spacecraft model in drake. For this, I am adding 3 revolute joints to the spacecraft base to simulate the torques applied on the base by the reaction wheels. Since URDF specification does not allow for spherical joints directly, I am using (pseudo) intermediate links to create a spherical joint. The relevant part of the urdf file is shown below:

<link name="Base"/>

  <link name="Base_roll"/>

  <!-- S/C Roll Joint -->
  <joint name="Joint_base_roll" type="continuous">
    <parent link="Base"/>
    <child link="Base_roll"/>
    <origin rpy="0 0 0" xyz="0 0 0"/>
    <axis xyz="1 0 0"/>
  </joint>

  <transmission name="Joint_base_roll_trans">
    <type>transmission_interface/SimpleTransmission</type>
    <actuator name="$Joint_base_roll_motor">
      <mechanicalReduction>1</mechanicalReduction>
    </actuator>
    <joint name="Joint_base_roll">
      <hardwareInterface>PositionJointInterface</hardwareInterface>
    </joint>
  </transmission>

  <link name="Base_pitch"/>

  <!-- S/C Pitch Joint -->
  <joint name="Joint_base_pitch" type="continuous">
    <parent link="Base_roll"/>
    <child link="Base_pitch"/>
    <origin rpy="0 0 0" xyz="0 0 0"/>
    <axis xyz="0 1 0"/>
  </joint>

  <transmission name="Joint_base_pitch_trans">
    <type>transmission_interface/SimpleTransmission</type>
    <actuator name="$Joint_base_pitch_motor">
      <mechanicalReduction>1</mechanicalReduction>
    </actuator>
    <joint name="Joint_base_pitch">
      <hardwareInterface>PositionJointInterface</hardwareInterface>
    </joint>
  </transmission>

  <!-- S/C Yaw Joint -->
  <joint name="Joint_base_yaw" type="continuous">
    <parent link="Base_pitch"/>
    <child link="Spacecraft"/>
    <origin rpy="0 0 0" xyz="0 0 0"/>
    <axis xyz="0 0 1"/>
  </joint>

  <transmission name="Joint_base_yaw_trans">
    <type>transmission_interface/SimpleTransmission</type>
    <actuator name="$Joint_base_yaw_motor">
      <mechanicalReduction>1</mechanicalReduction>
    </actuator>
    <joint name="Joint_base_yaw">
      <hardwareInterface>PositionJointInterface</hardwareInterface>
    </joint>
  </transmission>

  <!--Spacecraft-->
  <link name="Spacecraft">
    <inertial>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <mass value="2550"/>
      <inertia ixx="6200" ixy="48.2" ixz="78.5" iyy="3540" iyz="-29.2" izz="7090"/>
    </inertial>
    <visual>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <box size="2.2 2.1 2" />
      </geometry>
      <material name="Grey"/>
    </visual>
  </link>

The full urdf for the spacecraft+robot arm with reaction wheels can be found here:https://pastebin.com/0G1GSeqk and without reaction wheels can be found here:https://pastebin.com/v9Ne8Nv8

I use this to run the following script to apply a torque to the base and simulate the rotation of the system accordingly:

builder = DiagramBuilder()

# Adds both MultibodyPlant and the SceneGraph, and wires them together.
plant, scene_graph = AddMultibodyPlantSceneGraph(builder, time_step=1e-4)
# Note that we parse into both the plant and the scene_graph here.
Parser(plant, scene_graph).AddModelFromFile(SCpath)
# Remove gravity
plantGravityField = plant.gravity_field()
plantGravityField.set_gravity_vector([0,0,0])
plant.Finalize()

# Adds the MeshcatVisualizer and wires it to the SceneGraph.
meshcat = ConnectMeshcatVisualizer(builder, scene_graph, zmq_url=zmq_url, delete_prefix_on_load=True)

diagram = builder.Build()
context = diagram.CreateDefaultContext()
plant_context = plant.GetMyMutableContextFromRoot(context)
jointAcutation =  np.zeros((plant.num_actuators(),1))
jointAcutation[3] = 1
plant.get_actuation_input_port().FixValue(plant_context, jointAcutation)

simulator = Simulator(diagram, context)

meshcat.load()

simulator.AdvanceTo(30.0 if running_as_notebook else 0.1)

However, the Meshcat visualization only works without the reaction wheels part in the urdf. When I add the (pseudo) links and the joints the visualization is completely empty. Am I right to assume that this is due to the (pseudo) links in the urdf? If so, is the sdf format a better way to create spherical joints that they can also be visualized?

P.S I am trying to control the spacecraft attitude by applying torques on the base while moving the robot arm to simulate reaction wheels. I assume that adding a spherical joint would be the easiest way to add a "joint controller" to accomplish this. Maybe there is a better way to do this.

Update: This issue can be reproduced using the following notebook on Google Colab: https://colab.research.google.com/github/vyas-shubham/DrakeTests/blob/main/freeFloating/FreeFloatingTumbleTest.ipynb