I have a database with some students that makes their applications on the internet injected in a MySQL database. When I use the ODBC function to import new records, i choose the option "Add new records" box only. Not any updating etc.

But still the extra fields that I have in my FM Pro database gets deleted. What going wrong here?

do these fields have validation set to ALWAYS? Perhaps validation is failing thus not importing the data or records.

No the Always is not on. It look like this:

When was the last time you checked the field mapping on the import? Has the original or target table's fields been deleted - sometimes that will break and not give you desired results some fields hit wrong target fields or none at all.