EB Registration not Showing CB field

UPDATE: ON A BACKUP SITE, IF I DELETE THE FIELD cb_teachernumber FROM CB AND RECREATE IT WITH THE CONDITIONAL FIELDS AND REMAP IT THE the eb_TeacherNumber textfield DOES show.
SO IT MUST BE A DATABASE ISSUE. HOW CAN I FIX THIS?

Hi Tuan
I have EB 1.6.2 with CB 1.9.1
The user will register using CB registration.
One of the Reg fields is a CB conditional field dropdown with the following options
Teacher | Principal | NQT | Parent

If they select either "cb_type" Teacher | Principal | NQT they also have to enter a ID number - "cb_teachernumber" if they select "Parent" no ID number is required and this field is hidden in the CB registration - so far so good.

The cb_type and cb_teachernumber fields are mapped to the EB custom fields and are required fields = eb_RegistrationType and eb_TeacherNumber

To book an event the user logs in and the Event is activated for booking.
Everything works except on the EB Registration page if a user has selected NQT as an option the eb_TeacherNumber textfield DOES NOT show - only the title. If they select Teacher or Principal the the eb_TeacherNumber textfield DOES show

I have tried the following
Checked in Databases
Cleared all caches
Used Tools in CB to synchronize users / databases etc.
Ensured the CB conditional field cb_type includes NQT as an option to show the cb_teachernumber field

The option NQT was added at a later date and I am wondering if the database table needs to be manually updated to allow the
eb_TeacherNumber to show up.

Really appreciate any help on this issue.
Thanks