In Floorplan Editor, I cannot see some of the pins that have been LOC'ed in the UCF file. They appear in the Floorplan view, but not in the Package view. The design runs through implementation (specifically NGDBuild) without any problems and the pins are assigned correctly. Why do they not appear in Floorplan Editor?
This is a problem in Floorplan Editor where it does not recognize the bus delimiter in the UCF file unless it corresponds to the bus delimiter of the XST options. The default bus delimiter is <>, so if your UCF file contains entries similar to the following:
NET "my_bus" LOC = E18;
then you should either change it to:
NET "my_bus<2>" LOC = E18;
or change the XST synthesis options to use the bus delimiter that corresponds to your UCF (you must also make sure that your UCF uses the same bus delimiters throughout).