Odd. From the toolbar, EXPORT | VIDEO FILE. In the export box click the blue Default Quality / Filesize link. In the menu that appears confirm that it is set to Auto Detect.
Lossless can be overridden by turning it off. Click the chevron to the right of the words Auto Detect to see the drop-down menu.
If this doesn't help, first back up your project. Save Project File AS routinely, giving it a unique # or name, so as not to overwrite prior saves. Using Save Project Files (no AS) will overwrite. From the HOME tab, that choice is available by clicking the chevron to the right of the Save Project button on the toolbar.
Then install the current release. If the issue persists, come back here.