This answer record contains known issues for Vivado Design Suite 2013.x related to IP core flows, including IP customization, IP generation, IP Packager, IP Catalog and integration of IP cores in the Vivado design environment.
Solution
Known IP Flow Issues in Vivado Design Suite 2013.1
(Xilinx Answer 55293) - IP core port names have been converted to use all lower case characters in Vivado 2013.1