@Anh I'm having a similar issue to this...
Using:
MB Builder
MB User Profile
MB Front End Submission
My form fields are appearing, but...
1) Users don't have the option to edit from where they left off. It creates a new post every time and deletes previous information
2) I have User Registration fields mapped to 'Users', and a separate form as a "User Profile" mapped to another post type ( I'm using WPFacet and have the MB fields mapped to their UPT Users Post Type that makes Users searchable.) Every time I update the User Registration form fields it wipes the information from my 'User Profile' fields.
Help is super appreciated!