Data assist admin section has broken the front end version

For some weeks I have had a registration system based on your double opt-in working, and last night I created an admin section for the same table within the database and now the front end double opt-in has broken!

Registration is being validated, the form is submitting, emails are being triggered, but there is no record being created in the database!!!

Thinking about it, I also edited some of the server validation last night, but reverted back to their original settings. This WAS working fine yesterday on the live server prior to creating the admin section for the registered users and trying to remove some WA Server Validations and the respective spry validation regions.

I did all of this work locally, found it didn't work, so I deleted it, and reverted back by copying the working version from the live server. I then created the admin section and copied that and the webassist folder up to the live server to find that the registration is now broken.

I've checked the insert behaviour, and that all seems in order... I think!

What's happened?