Hey everybody. This has happened to me a few times this year. I'm not exactly sure what is wrong but I manage to figure it out typically by playing around with different things. Here's what I did this time.
1. Go to mail, contacts, calendars in settings.
2. Turn on iCloud contacts
3. Go to your adress book or favorites
4. Click on the info symbol to the right of one of your missing names.
5. Scroll down and click on add to existing contacts then cancel
6. Then click on create new contact then cancel
7. Then I exit app or I think it crashed and my names were magically restored.
I'm not sure why this worked but it did.
Good luck