Why my friend's Mi3 contact list show (no name) ?

My friend did something (she cant remember what she did) to her setting in Mi3. Then certain whatsapp contacts (other contacts) show no name in her contact list. These no name contacts cannot be edited but can be deleted by way of being hidden in the contact list. All her named and no name whatsapp contacts have +6 in front. Any solution?

I wanted to buy Mi3 ever since it launched in China last year. Even thinking of asking friends to buy from China but decided not to cos no local warranty. When AP sets are available, I held back from buying cos not keen in AP sets. In May when Xiaomi brings in Mi3 for online sale, I quickly tried to grab during the 1st batch but failed. Managed to buy it at RM889 the next day when cancelled orders were released back for sale.
So far I've managed to grab several Mi3 and power banks for my friends. They really love Mi3 and have no regrets buying this phone. One of them is an Iphone user and she is fascinated with Mi3.