If there is one single special character (like ö,ä or å) in beginning of additional field that field is not imported at all. If character is existing somewhere else than first character, only characters before that special character is imported (like Pöytyä -> only first character “P” is imported).
If csv-file character set is changed before importing (Notepad -> Encoding UTF-8) Phplist does not regognize fields at all and those have to be set manually.
I am using version 3.2.4.