Thank you for your report.
However, judging by how you described the problem, it sounds like the game wasn't able to save to disk. Saving to disk often happens when the game closes, even if it is by pressing the X on the upper-right corner of the window. (This is how the game engine I'm using works. Unity)
I will double-check this problem and see how I can improve this. However, I can't make any promises that I can make a fix to this.