If I open the Vivado IDE and attempt to customize or generate an IP core without a valid license, I correctly see an error stating that the license is not found.
However, if I then add the correct license, the customization GUI still does not find the newly installed license.
The License status viewed from the IP catalog does update correctly.
In Vivado 2012.x, the Vivado Integrated Design Environment must be closed and re-opened in order to see the newly added licenses.
This issue is fixed in Vivado 2013.1.