Why does libreoffice keep losing hours and hours of progress?

At first I thought I hadn’t configured it to auto-save. True enough–there was an unchecked option to save every 15 minutes (and then whether to save to file or just create a backup). So now with those options ticked, I proceed with my work. Yet it still seems that if I do anything less than exit cleanly (which seems to be anything less than going to the file menu and clicking exit libreoffice, I sure as heck can’t shut the machine down and expect it to be handled properly) the document recovery dialog will show the next time I launch, and if I dare to try and skip past this I will be set back to a version of the file that could be days old. What is going on?

I am suffering from the same problem in scalc (latest LO 5.1.2.2, Windows 64 bit)