I had 4 documents open in LO Writer that I was editing over a 24 hour period. One of the document windows froze (or became corrupted). I closed all instances of Writer and rebooted my laptop (Windows 10 Home). When I reopened the file I noticed the cover page had changed. I saw that the [page size was different. Checking Page Style showed that the page size had changed from Letter to B4.
I cannot imagine there was anything I did to cause this, but how could this happen? Is this a possible bug?