FileMaker's Import Records > File... feature has a 100% reproducible bug in which it misreads source data fields that contain line breaks. Attached is a video demonstrating the bug.
Given a CSV file containing this data:
Field A,Field B,Field C,Field D Record 1,Sherman Oaks,"15301 Ventura Blvd. Suite P-22",CA Record 2,Woodland Hills,21821 Oxnard St.,CA Record 3,Pasadena,"300 E. Colorado Blvd. Suite 218",CA Record 4,Thousand Oaks,2250 Thousand Oaks Blvd.,CA
FileMaker will misread the data if the user chooses not to import Field C and all subsequent fields.
FileMaker correctly reads the data if the user chooses to import Field C and/or Field D.
Here's my guess as to the cause of this bug: if the user chooses not to import Field C and Field D, FileMaker does not bother to read their contents. FileMaker does not notice the double quote enclosing Record 1 Field C, and therefore assumes that the following line of text (Suite P-22...) is the start of a new record. If read correctly, FileMaker would recognize Suite P-22 as a continuation of Record 1 Field C.