Product Feature: Work Center
A specific font that is installed in the Windows font directory cannot be used in a publication, although it is appearing in the font drop down list.
In this instance the font only contained Windows 1252 (Central European), so if the language in Designer was not one of the Central European languages, the font would automatically revert back to the default font, which is Arial 11pt.
ResolutionUPDATED: November 3, 2017
Check the properties of the font, and the code pages that are supported.