Registrations not being processed

I have been trying to de-couple the Membership registration process from the subscription payment process because my client does not want people to automatically lose their membership just because they are late with renewal payment. I was receiving advice from Sandeep Kumar but he hadn't responded to my latest inquiry before my WPMUDEV membership expired. See the thread here https://premium.wpmudev.org/forums/topic/paying-for-subscriptions-outside-membership#post-668140 I have now once again renewed my membership and need some serious help again.
On a separate but possibly related issue when a visitor wants to register as a member they are taken to the 'Create an Account' page but after filling our their details and clicking on 'Register my Account' nothing happens. They are taken nowhere and do not appear as a member or user in Wordpress. Something has broken down here. Please help. I can send admin access if supplied with an email address.