Product and version: FileMaker Pro Adv 17.0.2
OS and version: macOS Sierra 10.12.6
Hardware: Mac Pro
Description: The text "Nan" imports as 0 (zero) from an xlsx file.
How to replicate: Make an Excel spreadsheet. Type "Nan" in a cell. Save as default xlsx format. Import to a new table in FileMaker. Expected text "Nan" shows as 0 in the field mapping dialog and on import.
Workaround: Save Excel spreadsheet as older xls format.
I'm guessing the text "Nan" is being mistaken for "not a number."