I did try to use json to save the data and it was fine when I ran it in unity, but when I published it would have a problem (not every time) and I used a JavaScript script to fix it but it didn't seem to work, I'm sorry for messing it up.
maybe try and upload a new build? you can use player prefs in unity or just not have save data at all. some other people in the jam messed up their initial builds but uploaded a new one or put a new link in the descriptions
