Recent documents list gets cleared after app relaunch

Question

I have a non-document-based application in which I would like to use the "Open Recent" menu item to open a recently opened item. I've implemented this using application:openFile: and noteNewRecentDocumentURL: as described here.

AppDelegate.m (excerpt)

- (BOOL)application:(NSApplication *)theApplication openFile:(NSString *)filename {
    [self.someController openRecentDocument:filename];
    return YES;
}

SomeController.m (excerpt)

[[NSDocumentController sharedDocumentController] noteNewRecentDocumentURL:[NSURL fileURLWithPath:filePath]];

This seems to partially work initially, with the document appearing in the menu after calling noteNewRecentDocumentURL: but after relaunching the app, the "Open Recent" menu is empty.

Is there something else I need to do to get this to work properly?