This looks, based on the comments in unit tests I've found, to be related to #45970. I spotted it with #56737 In excel, if you create a formula which references a named range in another file, eg "TestFile.xls!NR_Global_B2", then ask POI to get you the formula of the cell, it will be returned without the filename, so you'll just get something like "NR_Global_B2" This seems to be related to how we decode things like NameXPtg / SupBookRecords etc