Hi,
One of the reasons why only the email may be showing up in the contacts list is because someone with that email address filled out a form on your site or a contact action related to that email was performed on the site before the name and email was registered as a site member.
In order for us to really see why this may be happening and run some tests, send us your site name and URL so we can take a look at what may be causing this.
Thank you, we await your reply.
Edward