I played it last night and got four different endings; when I relaunched it today, my gallery progress was gone!
Any idea how to prevent this from happening?
hmm, unfortunately I'm not sure why. do the two files in the 'persistent' folder look as if they have been created around the same time that you played this game?
one suggestion I can make is to have a folder called "Ren'Py Data" in the root folder where the unzipped game folder is, and renpy should automatically save the save files there, but that won't bring back the saves you've lost.