Registration Error: First_name and Last_name not saving

Responsive Real Estate: 5.6

• My registration form requires new users to input FIRST NAME and LAST NAME.
• I’ve customized the registration form using database input fields (first_name) and (last_name)
• When a user completes these in registration, they are NOT being saved/stored
• The fields remain blank in MY ACCOUNT DETAILS, Admin > USERS and in database
• If a user then adds these in MY ACCOUNT DETAILS, they are then saved

Seems that the fields are not linking/ mapping from the registration form but are doing so once logged in? Other registration form detail is saved e.g. Country of Residence.

Can anyone suggest anything that may be going wrong?

Things I’ve tried:

I have deleted and re-created the registration form but no luck

(Screenshots in next reply)