I'm not sure exactly how to fix this problem, however, I can tell you what I've experienced. Everytime the game does this to me I have to reinstall because I can never find a way to fix it.
Also, in the future when you're making maps, I suggest downloading another FeralHeart and naming the folder something else such as "FH" or "FeralHeart2" and creating your maps on there instead of the game you play on. This helps so that you don't have to completely start over if it comes down to reinstalling the game. It's also easier since your exports will have nothing in them so when you export the map you'll be able to only see the files that you have just exported from the map you created!
Hope this helps, and if you have any questions, feel free to PM me!