My categories are missing names

I have established multiple categories (distribution lists) in Windows Live Mail.  When I use Hotmail.com  (I know, I know it's now Outlook now) from my web browser to create an email and specify a category in the To: block, all names appear.  However, when I use Windows Live Mail 2012, some of the names are missing and sometimes no names appear.  If I go to the contacts page to view the category, all of the names appear.  If I edit the category, names are missing.  This is an unacceptable issue and needs immediate attention.  The problems exists on all four of my PCs.