I just spent several (18+) hours building a small game, mostly just to test what I could do and things like that. I saved repeatedly, exited and loaded repeatedly, all with no issue.
I had called the project by a filler name because I hadn't decided what I was actually going to call it. Later on, when I actually thought of the name I wanted, I changed the name of the folder from within the program itself. After that, things started to get weird. The name change of the folder wasn't reflected in map hierarchy view on the side of the display. Then I tried to open another file. When it asked me if I wanted to save, I hit "yes".
It didn't just save, and brought me to the "Save As" screen as if I had never saved it before. I thought it was weird but had something to do with me changing the name of the folder. So I went into that folder, named my file and hit OK.
It didn't open the file I'd tried to open. I tried again, the same thing happened, brought me to the "Save As" screen as if I hadn't ever saved it before. I tried to quit so it would ask me to save again. Same thing, and when I tried to hit OK after picking where to save, the prompt just vanished and the program didn't quit.
I retried several times and then faced facts that I'd have to quit without saving. So I did. The file is gone forever, despite hundreds of successful saves BEFORE this all started happening.
I don't know if this is a documented bug, but it crushed me. I am crushed.