Why are search results incomplete for primary contact/affiliation?

When I do a search for an organization to see who are our affiliated contacts (people who have indicated the organization as their primary affiliation - employer, typically) - my search results are incomplete. For example I searched for an organization and the Account came back plus 5 Contacts - but not the primary contact. Both the contact and the account records show each other as the primary affiliation/contact - but why doesn't it show? Also, I get a different result if I put an asterisk at the end of the organization name for the search - even if it spelled EXACTLY as the Account Name (with and without the asterisk) - and the search is not setup to be exact matches only. Ideas? Is this a known issue? Thanks for any insight/help on this.