https://network.genius-material.com/
The first field says username or email address. I believe that's causing confusion and may shed some light on the problem.
First, the new contact isn't aware they've set up a user name. They were asked for Full Name in the registration form and not a name.

https://network.genius-material.com/
The login form auto-populates with the wrong field in the lightbox

https://staging.genius-material.com/contact/

https://lysetteoffley.com/contact/
