This isn't a bug. Any values that are the same as a character's defaults are no longer written to saves. For example, say there is a character that you can only give new powers. Rather than saving every single value for the character, I only need to save the powers and can use the defaults to fill in the rest on load. This reduces the amount of space each persistent character takes up by a lot and will ensure that saves don't bloat once there are many stateful characters. You can manually add the fields and values back to the save file if you want.
P.S. Save editing isn't supported. It's allowed, but it's not supported. Meaning save-editing support doesn't go into design decisions.