How does the saves actually work?

Yesterday I started the game for the first time, played ~3h then closed the game after saving at a statue, some time after I restart the game and nothing was available to load.

I restart the game again with a new game, go up to the first statue, save then quit. And here it's available to reload. Then this morning while wanting to go back to were I was, nothing available to load again... I don't understand :/

I am on Windows 10
My games are installed in C:\Games\
the saves are stored at %USERPROFILEù\Documents\Chasm
For what I saw it create a directory "191104384486978675" inside and make a slot0.sav file that contain the save I guess, the backups dir have a 191104384486978675_slot0.sav this is the previous one I guess, and the Saves directory is just empty.

Did I miss something? It do not seem to be a bug since I found nothing about saves issues while searching, I admit I am a little lost for now

Thank you for your quick answer!

I do not use GOG cloud save feature, but after some more try and loss, it's definitively linked to GOG Galaxy, I am not sure what it does exactly, but just lauching it mess the saves somehow.

I started a new game this morning as a stand alone game without it linked to galaxy, everything worked well, I had an hour of game saved and could reload it later without issues, but after simply starting galaxy then closing it, a new lauch of the game erased the save again :/

I will look how to better reproduce and explain the issues but it is definitively linked on how the game and gog galaxy interact together

Edit:
Here are the step done

- cleaned save directory be erasing everything to be sure
- start a new game with Chasm.exe directly
- create the character, go to the first statue, save then quit
- relaunch the game again with Chasm.exe, the save is still there and work
- start GOG Galaxy
- close GOG Galaxy
- relaunch the game with Chasm.exe, the save has dissapeared

new edit:
after some time have passed... (Galaxy completly removed for system memory?)
- relaunch the game with Chasm.exe, the save has came back... I am a little lost here...