I am a historian. I have been using LibreOffice for years, maybe 15 or so.
I have been working on a scholarly paper. When I pulled it up today it was blank, although I save constantly & have an automatic save.
Every saved paper I have pulled up to look at is blank.
I use LO 6.1 on a Windows 10 machine.
The particular paper with which I am concerned is 30 pages. It swallowed words from a variety of documents from one page to 80.
I have written and published 3 books & 20+ articles in LO so I have felt reasonably competent with it.
When I save things myself, it is every page, and often every new change.
I tried turning off the machine & letting it sit for a while. When I turned it back on, there seemed to be no problem with any pages, except with the 8 that had been in the original LO screen when I first pulled it up. So I cannot get back the pages on those, but everything else is all right.