I couldn't figure out why some of my contacts were not being updated, the names were correct! It took me a while to figure out that when I imported the contacts from my old phone it added a space after the first name for every contact, which obviously couldn't be seen. After removing this space Hermes updated them all perfectly (except one, which for some reason although recognised by Hermes, the picture won't update). Perhaps Hermes should automatically trim the before and after spaces on the names prior to matching?