When a TFS 2013 user views a project web site, they want to assign a bug or requirement directly to a user from the results of a query they selected out of their "Team Favorites" in the left menu panel. The result on the right panel of the page page is a list of work items, and you can left-click any work item to "assign to" somebody. Unfortunately, when assigning items this way our list of possible people only shows A through part of "M". When clicking on the work item, you can assign it to anybody.
Any ideas what's causing this?