I just installed the membership plugin and discovered when a new user tries to register, chooses the subscription level and clicks "Register My Account", it goes to a blank "mydomain.com/register?action=validatepage1". I am running the 22.214.171.124 version of the Membership Premium plugin.
I just tried using the new beta from https://premium.wpmudev.org/forums/topic/authorizenet-gateway-beta-release#post-552192 , and there is no change. I still end up with a blank "validatepage1" page. Any help on this would be great.