Infusionsoft Optin Forms giving "invalid email" error

Recently, all optin forms created in wordpress are giving back an “invalid email” error when trying to sign up. This is happening on all existing forms, as well as newly created forms.

Forms which are created in the plugin are showing in IS when creating a campaign, so the two sides are talking, however does anyone know what to do about this issue? I called support and they say it’s a Wordpress Issue, WP says it’s an IS issue.