To solve the problem you will need to delete a hidden file called SSI-Web_Forms.settings
from your computer that is installed when you run SSI Web for the first time. It was corrupted somehow and will rewrite itself if it can't be found. It stores the form settings in a JSON format (JavaScript Object Notation) and is the only code that is used by the JsonReader. In your search bar in Windows Explorer, search for a file called: SSIWeb_Forms.settings. An example path for the file might be something like this:
C:\Users\Profile_Name\AppData\Roaming\Sawtooth Software, Inc\SSI Web
Once you find the file, delete it, and restart SSI Web. It will recreate the file.