Tried a few things and I couldn't replicate it. Downloaded 0.23, started new game, saved, quit loaded and everything worked fine.
Downloaded 0.20, new game, save, transfer save to 0.23 ant it still worked.
Does that error show up when no old saves are present and you make a new one, or did you try to load saves from 0.20?
Also, could you please put your save files into a zip and send them to my email? Would make my work much easier.