Yeah it's to do with the patches, I noticed your Editor only worked on a non patched game save, with no patch its ".sav" with the patch applied its ".savtu" once the patch has been applied it's irreversible it seems even if you rename it to .sav to open into your editor the patch changes the save game so it work work because I'm guessing you set your editor to read just .sav ? hope this helps (if you didn't already know lol)