Missing fixed frame in my model

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Why isn't Gazebo 9 displaying the tip's frame? Using RViz, you can view the frame as shown in the below image. In addition, I can't see the link listed under the model in Gazebo. There seems to be no visualization of fixed frames. Gazebo only displays one fixed joint, which connects the world and base link.

The urdf file for this link is

    <link name="tip"/>
    <joint name="tip_joint" type="fixed">
        <parent link="mid_link"/>
        <child link="tip"/>
        <origin xyz="0 0 ${height2}" rpy="0 0 0"/>
    </joint>