controller_manager not publishing /joint_state topic

edit

I am a ROS beginner so this might all be a rather basic mistake. But I have a simulation of a drone in Gazebo. I am using controller_manager to spawn controllers for the propellers and a camera. However, robot model in Rviz gives me a lot of no transform link errors because /joint_state topic is not being published.

Here is my control.yaml file

joint_state_controller:
  type: joint_state_controller/JointStateController
  publish_rate: 50

joint_motor_controller:
  type: velocity_controllers/JointGroupVelocityController
  joints:
    - front_left_prop_joint
    - front_right_prop_joint
    - back_left_prop_joint
    - back_right_prop_joint

camera_joint_position_controller:
  type: position_controllers/JointPositionController
  joint: camera_joint

drone_base.xacro

<?xml version="1.0" encoding="utf-8"?>
<robot name="drone_description"
  xmlns:xacro="http://www.ros.org/wiki/xacro">
  <xacro:property name="PI" value="3.14159265359"/>

  <xacro:include filename="$(find drone_description)/urdf/drone_macros.xacro" />
  <xacro:include filename="$(find drone_description)/urdf/drone_gazebo.xacro" />
  <xacro:include filename="$(find drone_description)/urdf/sensors.xacro" />

  <!-- DUMMY lINK -->
  <link name="dummy_link" />

  <!-- LINKS -->
  <link name="base_link">
    <inertial>
      <origin xyz="5.7334E-07 0.026879 0.015324" rpy="0 0 0" />
      <mass value="0.38016" />
      <inertia ixx="0.00029212" ixy="-1.331E-09" ixz="-3.9126E-08" iyy="0.00040699" iyz="1.6869E-06" izz="0.00015798" />
    </inertial>
    <visual>
      <origin xyz="0 0 0" rpy="0 0 0" />
      <geometry>
        <mesh filename="package://drone_description/meshes/base_link.STL" />
      </geometry>
      <material name="">
        <color rgba="0.69804 0.69804 0.69804 1" />
      </material>
    </visual>
    <collision>
      <origin xyz="0 0 0" rpy="0 0 0" />
      <geometry>
        <mesh filename="package://drone_description/meshes/base_link.STL" />
      </geometry>
    </collision>
  </link>

  <link name="camera">
    <inertial>
      <origin xyz="-0.0036143 0.00349 0.00925" rpy="0 0 0" />
      <mass value="0.090718" />
      <inertia ixx="2.4903E-06" ixy="3.2829E-09" ixz="8.2525E-22" iyy="3.279E-06" iyz="-1.531E-21" izz="2.3388E-06" />
    </inertial>
    <visual>
      <origin xyz="0 0 0" rpy="0 0 0" />
      <geometry>
        <mesh filename="package://drone_description/meshes/camera.STL" />
      </geometry>
      <material name="">
        <color rgba="0.69804 0.69804 0.69804 1" />
      </material>
    </visual>
    <collision>
      <origin xyz="0 0 0" rpy="0 0 0" />
      <geometry>
        <mesh filename="package://drone_description/meshes/camera.STL" />
      </geometry>
    </collision>
  </link>

  <!-- DUMMY JOINT -->
  <joint name="dummy" type="fixed">
    <parent link="dummy_link" />
    <child link="base_link" />
  </joint>

  <!-- JOINT -->
  <joint name="camera_joint" type="revolute">
    <origin xyz="0.00925 0.059965 0.0165" rpy="${PI/2} 0 -${PI/2}" />
    <parent link="base_link" />
    <child link="camera" />
    <axis xyz="0 0 1" />
    <limit lower="0" upper="${PI/3}" effort="100" velocity="1" />
  </joint>

  <transmission name="camera_trans">
    <type>transmission_interface/SimpleTransmission</type>
    <joint name="camera_joint">
      <hardwareInterface>hardware_interface/PositionJointInterface</hardwareInterface>
    </joint>
    <actuator name="camera_motor">
      <mechanicalReduction>1</mechanicalReduction>
      <hardwareInterface>hardware_interface/PositionJointInterface</hardwareInterface>
    </actuator>
  </transmission>

  <xacro:prop_link name="front_left_prop" />
  <xacro:prop_link name="front_right_prop" />
  <xacro:prop_link name="back_left_prop" />
  <xacro:prop_link name="back_right_prop" />

  <xacro:prop_joint name="front_left_prop" originxyz="-0.092959 ...