Which OS? mac, windows, version of those?
I am using the file on Both Mac Lion and Windows 7
Any new printer drivers involved in this issue?
I'm sitting in front of a windows xp machine with FileMaker 12 installed on it. I can select Printer Setup from the File menu, then select a printer for whch I have specified a pair of custom paper sizes long before installing version 12 and the custom paper sizes are still present in the paper size drop down for that printer.
That may simply mean that the issue is specific to Windows 7 and Mac Lion as I don't have access to those versions at the moment to test this.