Version Found: v1.4
Version Resolved and other Known Issues: See(Xilinx Answer 45195).
When creating a custom memory part in the MIG GUI, the tREFI parameter is not generated correctly. For example, when setting the tREFI parameter to 3.9 microseconds, the generated MIG rtl sets the tREFI to 7.8 microseconds.
This is an issue in the MIG GUI when generating a custom memory part and can be worked around by manually modifying the tREFI parameter value in the top-level module of the MIG design.