I have recently installed this extension and I found that it was necessary to make a single character change, to add an ampersand, in order for the preferences to be shown.
I downloaded the "Git master" snapshot on 2013-03-22 and it was necessary to change, in BreadCrumbs.php:
function fnBreadCrumbsAddPreferences( $user, $defaultPreferences ) {
to:
function fnBreadCrumbsAddPreferences( $user, &$defaultPreferences ) {
I don't know enough about the GetPreferences hook to know if the requirement to add the & is a peculiarity of my installation, or the way that things should be. --79.98.163.245 10:55, 25 March 2013 (UTC)