Spherical joint limit not taken into account

I’ve been testing Isaac Gym using one of our mujoco file of a robot with a spherical joint.
Here is an example:

            <body name="thigh_FR" pos="1.89 -1.53 -0.85" quat="-1.7 0.1 0.3 1">
                <joint name="hip_FR" type="ball" pos="0 0 0" axis="1 0 0" limited="true" range="0 0.5" />
                <geom class="robot:Visual" name="thigh_FR" mesh="thigh" pos="0 0 0"/>
                <body name="shin_FR" pos="3.50 0 -5.60" quat="0 0.383 0 0.924">
                    <joint name="knee_FR" pos="0 0 0" axis="0 1 0" type="hinge" limited="true" range="-0.785398 0.785398"/>
                    <geom class="robot:Visual" name="shin_FR" mesh="shin" pos="0 0 0"/>
                    <geom class="robot:Collision" name="shin_FR_collision" type="box" size="0.4 0.4 3" pos="0 0 -4"/>
                    <body name="foot_FR" pos="0 0 -7.95" quat="1 0 0 0">
                        <joint name="ankle_FR" pos="0 0 0" axis="0 1 0" type="hinge" limited="true" range="-0.785398 0.785398"/>
                        <geom class="robot:Visual" name="foot_FR" mesh="foot" pos="0 0 0"/>
                         <geom class="robot:Collision" name="foot_FR_collision" type="box" size="0.5 0.5 0.4" pos="0 0 0"/>
                   </body>
                </body>
            </body>

Unfortunately, the limits set on the spherical joint are not taken into account.
I’ve tried setting it manually via the asset DOF properties for the 3 DOFs created by the spherical joint, but it had no impact.
I would have expected the ball joint to be represented by a D6 joint with the twist and swings representing the limits.
Is there anything special to set or do you see any issues with the mujoco example above?

I’ve tried using multiple joints, as the humanoid_CMU_V2020_V2 (see below), but same issue.

            <body name="thigh_FR" pos="1.89 -1.53 -0.85" quat="-1.7 0.1 0.3 1">
                <joint name="hip_FR_0" pos="0 0 0" axis="1 0 0" limited="true" range="-0.5 0.5"/>
                <joint name="hip_FR_1" pos="0 0 0" axis="0 1 0" limited="true" range="-0.5 0.5"/>
                <joint name="hip_FR_2" pos="0 0 0" axis="0 0 1" limited="true" range="-0.5 0.5"/>
                <geom class="robot:Visual" name="thigh_FR" mesh="thigh" pos="0 0 0"/>
                <body name="shin_FR" pos="3.50 0 -5.60" quat="0 0.383 0 0.924">
                    <joint name="knee_FR" pos="0 0 0" axis="0 1 0" type="hinge" limited="true" range="-0.785398 0.785398"/>
                    <geom class="robot:Visual" name="shin_FR" mesh="shin" pos="0 0 0"/>
                    <geom class="robot:Collision" name="shin_FR_collision" type="box" size="0.4 0.4 3" pos="0 0 -4"/>
                    <body name="foot_FR" pos="0 0 -7.95" quat="1 0 0 0">
                        <joint name="ankle_FR" pos="0 0 0" axis="0 1 0" type="hinge" limited="true" range="-0.785398 0.785398"/>
                        <geom class="robot:Visual" name="foot_FR" mesh="foot" pos="0 0 0"/>
                         <geom class="robot:Collision" name="foot_FR_collision" type="box" size="0.5 0.5 0.4" pos="0 0 0"/>
                   </body>
                </body>
            </body>

From the documentation, it looks like such a configuration should be supporter:

The MJCF importer supports multiple joints between a pair of bodies, which is useful to define independently named and controllable degrees of freedom. This is used in the humanoid_20_5.xml model to define independent motion limits for shoulders, hips, and other compound joints.