So, near as I can tell, how I lost all of my saved versions is partly the beta fix not working on my system and partly (OK, mostly

) my own fault. I did a quick save, which failed. When I went back into the game I didn't notice that the previous quick save was gone, since the last attempt failed. Then the game did an auto save, which also failed, wiping out the last auto saved game. Then I did ANOTHER save, but accidentally hit the "Save/Load" instead of quick save. That ALSO failed, but wiped out the only existing saved version, which was the previous auto save. Voila! A perfect storm of stupidity!