Import into a choice field does not import all values

Hi all.

Trying to convert a database from FileMaker Pro (FM) to Ninox.

In the FM document, I have a field ("dropdown list") that offers three choices ("A", "B", "C").  But it also allows some records to contain values other than "A" or "B" or "C".

I created a Ninox db with a choice field and imported the FM (previously converted to .csv) db.

Those records that contained "A" or "B" or "C" were imported correctly.

HOWEVER, those records that contained another value were imported with NO VALUE!!!  (This happens to be the default value of the choice field).

How can I import all the values into that choice field?

Thanks!