I'm glad I decided to create my own save/load in my current project by writing/reading file instead of relying on the built-in method.
Test it for 0.13 alpha 5, see if it works.
The only difference between using the default save/load to the custom file write/read is that you have better control of what data is saved, but the file still needs to be stored somewhere.
This is where the bugs are crippling. The new NW.Js ignores your set data path, it sets its own temporary folder so your file isn't there to be retrieved in the next play session.
I had a Nexus 5 mobile from Google. An Android update broke my mic/earpiece function, the phone would only work to make calls with headphones. This was an official Google product which they charged a lot of $ for and they screwed it up badly. I have NO faith that Google knows what they are doing.
This is why reliance on them to get Chromium right, for C2 and later C3 to function well, is a mistake.
Edit: Can't seem to test with the C2 NWjs object (for file control) for the new 0.13.alpha5, project exported with that object fail to start and just hangs, but without the object its fine.