Gazebo not loading certain links

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The urdf was loading just fine before, but I am trying to add an arm and those links will not load. All parts load in rviz, but not in gazebo. I have tripple checked the syntax, but I can not find an issue. This is the urdf for those parts

<joint name="arm_joint" type="continuous">
    <parent link="base_link"/>
    <child link="arm_link"/>
    <origin xyz="${base_length/2} 0 ${base_height/2}" rpy="0 0 0"/>
    <dynamics damping="0.5" friction="0.1"/> <!-- get real later-->
    <limit effort="1000" velocity="10"/> <!-- simmulate motors, max velocity and max joint effort -->
    <axis xyz="0 1 0"/> <!-- will rotate for y axis -->
</joint>

<link name="arm_link">
    <visual>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <geometry>
            <box size="${arm_length} ${arm_width} ${arm_height}"/>
        </geometry>
        <material name="orange"/>
    </visual>

    <collision>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <geometry>
            <box size="${arm_length} ${arm_width} ${arm_height}"/>
        </geometry>
    </collision>

    <inertia>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <mass value="${arm_mass}"/>
        <box_inertial_matrix m="${arm_mass}" h="${arm_height}" l="${arm_length}" w="${arm_width}" />
    </inertia>
</link>

<joint name="digr_joint" type="continuous">
    <parent link="arm_link"/>
    <child link="digr_link"/>
    <origin xyz="${arm_length/2} 0 0" rpy="0 0 0"/>
    <dynamics damping="0.5" friction="0.1"/> <!-- get real later-->
    <limit effort="1000" velocity="10"/> <!-- simmulate motors, max velocity and max joint effort -->
    <axis xyz="0 1 0"/> <!-- will rotate for y axis -->
</joint>

<link name="digr_link">
    <visual>
        <origin xyz="0 0 0" rpy="${PI/2} 0 0"/>
        <geometry>
            <cylinder length="${digr_height}" radius="${digr_radius}" />
        </geometry>
        <material name="purple"/>
    </visual>

    <collision>
        <origin xyz="0 0 0" rpy="${PI/2} 0 0"/>
        <geometry>
                <cylinder length="${digr_height}" radius="${digr_radius}" />
        </geometry>
    </collision>

    <inertia>
        <origin xyz="0 0 0" rpy="${PI/2} 0 0"/>
        <mass value="${digr_mass}"/>
        <cylinder_inertia m="${digr_mass}" h="${digr_height}" r="${digr_radius}"/>
    </inertia>
</link>

and this is the .gazebo

    <gazebo reference="arm_link">
    <material>Gazebo/Orange</material>
    <mu1>0.3</mu1>
    <mu2>0.3</mu2>
</gazebo>

<gazebo reference="digr_link">
    <material>Gazebo/Purple</material>
    <mu1>0.3</mu1>
    <mu2>0.3</mu2>
</gazebo>