I have a single user on Outlook 2010 that keeps losing his contacts. We're on exchange 2013 latest patches. I've verified that the user isn't accidentally deleting them. I will restore his contacts from a backup file and within a day they're gone. Sometimes I'll find them in his deleted items folder. I've got his retention policy set for 90 days (don't think this has anything to do with problem).
I'm at a lose.