Program locks up and CPU usage skyrockets if I try to save anything in .xlsx format; ODS and csv work fine with the same file.
Please tell us your LibreOffice version. Which Linux distro & version? Is it for every file, even an empty file? If not, you have to attach the .ODS file here. Set to NEEDINFO. Change back to UNCONFIRMED after you have provided the information.
No reply for more than a year. Closing due to lack of information.