Context: https://github.com/SheetJS/sheetjs/issues/2011 The reported issue involves: - file parsed by the XSSF library - a cell was programmatically added using createRow/createCell API calls - updated file was written The user provided a sample file, attached to the GitHub comment https://github.com/SheetJS/sheetjs/issues/2011#issuecomment-646472892 Inspecting the file, POI appears to have added cells E8/F8 but did not update the worksheet range to include the new cells. Is this known / expected behavior?