It seems to be like this hope so these character will helps you. Kindly perform the steps mentioned below for issue resolution :
Go to Settings -> Apps -> (On the right top corner you will find 3 dots click on it) -> Tap on reset app preferences.
Go to Settings -> Apps -> Contact manager : Clear cache, Clear data -> Contact Storage : Clear Cache, Clear data
(Take all your contacts backup before performing this step as it will erase all the contacts)
Restore the contacts. Hope this helps.