Why does SDO_AGGR_LRS_CONCAT_3D clip (zero out) the third dimension in the resulting geometry?

Question

Doing:

        SELECT SDO_AGGR_LRS_CONCAT_3D(SDOAGGRTYPE(
            SDO_GEOMETRY(z.SDO_GTYPE, z.SDO_SRID, z.SDO_POINT, z.SDO_ELEM_INFO, z.SDO_ORDINATES), 
            0.005))
        into l_geoloc
        from (select * from TABLE(Pi_geom_array)) z;

Pi_geom_array is series of rows:

1. MDSYS.SDO_GEOMETRY(4402, 4326, NULL, MDSYS.SDO_ELEM_INFO_ARRAY(1, 2, 1), MDSYS.SDO_ORDINATE_ARRAY(-87.5471018117985, 41.6482888766313, 588.16578218591, 506.44231, ...)
2. MDSYS.SDO_GEOMETRY(4402, 4326, NULL, MDSYS.SDO_ELEM_INFO_ARRAY(1, 2, 1), MDSYS.SDO_ORDINATE_ARRAY(-87.5471018117988, 41.6482888766318, 588.16578218598, 506.44238, ...)
3. etc...

l_geoloc is: MDSYS.SDO_GEOMETRY(4402, 4326, NULL, MDSYS.SDO_ELEM_INFO_ARRAY(1, 2, 1), MDSYS.SDO_ORDINATE_ARRAY(-87.5471018117985, 41.6482888766313, 0, 506.44231, -87.5471437282998, 41.6483175668031, 0, 506.44531, ...)

where the SDO_ORDINATE_ARRAY is correct union of input SDO_ORDINATE_ARRAY's. But where the z index are all zeroed out.

Why is this occurring? There doesn't seem to be lot of documentation out there on oracle spatial functions. Is there a setting somewhere else, or how the function is being called that's causing this? Or is there an error with the SDO_AGGR_LRS_CONCAT_3D 3d function perhaps..?

New to oracle spatial...

The third dimension i.e. z values (since this is 3D version of the function) should not be zeroed out...