I am trying to use the Wix Members app and create a custom sign up form to collect some more data when a user signs up. I have the form created and when I access it in a live version of the site, it work and adds a new contact/member. But when I try to enable the custom signup, it gives me the option to select a lightbox (so I made my form a light box), I can see the light box in the list, I can select it but every time I click done, the "What does it link to" field is still blank and I can't click save. Below are some screenshots of what it looks like. Any help would be greatly appreciated.