Created attachment 29381 [details] Example with the problematic formula I am using the HSSFListener. Type the following formula: =IF(1=1,"","abc") Excel shows nothing (empty string) while FormatTrackingHSSFListener.formatNumberDateCell(formula) returns 0 The attachment contains the formula with problems. The attachment also contains other formulas that work correctly: numbers and strings. I have debugged the code and the string formula values are cached except for the one in the bug.
In the attachment, A9 is the cell with the empty result formula.