Maybe worth trying an alternative OS with a different kernel entirely from Linux, as a live USB. For example Haiku or ArcaOS?
However if you've tried Windows and not had the issue then it may not add anything as you nay already have excluded defective hardware?
It's nice to see the suite is still being developed, and kudos to such a small team for making such polished software.
My only caution is the sidebar design decision may be problematic? That's an awfully large amount of screen real estate being taken up compared to the Tab/Ribbon design used by other Office software. That is particularly important as it reduces the width available for a document and so squashes reducing the size of text etc on screen. Some of that may just be preference but that might also have impact for accessibility for people with sight impairment.