Ok I was being a numpty, I hadn't turned on SMS and email in the Registration Page settings! Thanks - your answer pointed me in that direction.
Could I also ask - is there a way of making the SSID work like this?:
1 - device connects to SSID
2 - device is MAC-auth'd
3 - If MAC auth fails device is redirected to registration page, otherwise device is authenticated onto network via MPSK.
ie is there a way of making this so that the user/device doesn't need access to the internet via another means (different SSID/wired/mobile) to do the registration part?