By default the M_AXIS_MM2Sand S_AXIS_S2MM bus interfaces are not added under the ports tab. To add these, check the "Port Filters -> By Connection -> Defaults in the XPS System Assembly view on the far right of the GUI.
Note: The XPS tool will add a buffer by default on all external ports. To stop the tools from doing this, use the buffer_type=none keyword in the external port definition in the MHS file in XPS. See (Xilinx Answer 53769) for help here.
Note: This flow is not tested by Xilinx.