When I import I/Os from CSV with the differential pairs labeled, PACE and Floorplan Editor do not treat them as pairs. When will this issue be fixed?
To work around this issue, place the differential pins separately.
This problem has been fixed in the latest 9.1i Service Pack available at:
http://www.xilinx.com/xlnx/xil_sw_updates_home.jsp
The first service pack containing the fix is 9.1i Service Pack 1.