Hi,
I think that your template overrides the output of the Joomla users component, so the tabs not work properly.

Registration/Edit profile page are the same of Joomla, tabs are generated by a javascript, but when the template overrides the output not along the lines of the default component, so, tabs not work. This is not bug of your template, this is simply a choice of the developer of the template.

Try to check if you your template override the output or try to disable tabs from Easy Profile options.

to check overrides:
- check if exists this folder /templates/your_template_folder/html/com_users
- if exists try to rename into /templates/your_template_folder/html/com_users.old


if you want we can try these things for you, but to do this we need your site details, if you want you can use the form below the reply in "Site details" tab.