I opened a xlsx spreadsheet in LibreOffice only to find out that the cells containing regular and italized text were messed up after saving. I.e. if a cell contained mmm in italics, followed by a space and then the text "Test" non-italized, as in "mmm Test", the cell contained only italicized characters after saving it as xlsx. In addition, spaces were removed! This has caused a major headache and hours of work as I have had to manually fix cells in 378 rows by 8 columns. Hope you can do something about this soon. Can't believe this has never been noticed before.
*** This bug has been marked as a duplicate of bug 92296 ***