Created attachment 75162 [details]
When saving the file in attachment as .xlsx (Microsoft Excel 2007/2010 XML), defined function on cell (matrix multiplication) C4 disappears. Also, if you save it to the older fomat (.xml, Excel 2003), this conversion works correctly.
Can confirm this bug with LO 4.1b1 on OS X 10.8.3. -> NEW.
*** This bug has been marked as a duplicate of bug 61908 ***