Thank you for this hint!
Yes this game has an autosave, on two slots that alternate. Is your dissapearing save game that one from the autosave or from a manual save?
Unfortunately, I'm not able to re-script the autosave feature on my own, so I'm afraid we have to deal with this, sorry :(
Love to hear that you enjoy the game despite this issue. Hope it will work in the downloaded version, so you can enjoy the rest too :)