Attention players!
I have found a fix for the bug which prevents you from closing menus and finishing characters. It seems to be a common bug, and it's affected me too.
This might not work for everyone, but it works for me.
Manually delete your game and files, and reinstall it
Go into C:\Users\[Your Username]\AppData\LocalLow\SolitaryScribbles\ChubChompChill and delete the file named "SaveFile.es3"
Launch the game directly (I haven't tested it using the launcher) and the menus should work again. It worked for me, so I hope it works for the rest of you too.