I loaded an unedited epub into Sigil. Then edited it section by section, formatting using html and editing the text.
I created chapter breaks for each section I wanted to appear on a new page. There were about 60 of these. I planned on merging them later.
I hit Ctrl-S for each section and renamed it, ie., Book Three a.xhtml; Atropos XI.xhtml, etc. Then edited and saved.
I closed Sigil after a few days of this editing and reopened the file. The last two days of edits were gone.
It looked fine until I closed it. Upon reopening it had reverted to a March 21 version. The March 23 version (finished) is gone. I lost 20 hours of work.
Any thoughts? Thanks Mark