I have the same issue. I am IT support for a company and took one of our phones to a certified Apple store with no help. I then took the phone to a squad of geeks but I will not say their name :-). I called Apple and they said to bring it to the closest Apple store. This was a 2 hour drive for me one way. I was told they are unsure about the disappearing contact name issue but they wanted to replace my battery. So I agreed to the battery replacement, unfortunately they didn't have one in stock so guess what, I need to come back in 4 to 5 business days when the get one in stock. 4 Days later I make the drive back to yet again another surprise. At this point I'm told they can't replace the battery because of a security risk!! So they gave me a new phone. My contact disparaging trick went away.... for 3 days and came back. I called Apple back and for the most part completely walked away from my issue and told me to start from scratch.
I have completely lost faith that Apple with fix or even address this issue. Just as Apple's logo suggests you are providing only a partial product. Goodbye Apple you have just received my last dollar.
With all the love in the world,
Grammy Smith