Something similar is happening to me, I've noticed yesterday around noon that new text messages were no longer displaying using people's name.. looked my contacts on phone, from People app on Windows 8.1 and online at outlook [dot] com.. everywhere was showing that I no longer had any contacts.. what happened?! Still don't have any contacts today. I know lately Microsoft is having some cloud services outages (example: Office 365), maybe it is related, maybe it is only isolated to just some people, one thing is sure is that it sucks! I won't be able to trust their services again to keep my contacts. I'm glad my calendar is not affected but I highly consider moving my data elsewhere!