Thanks, I will give it a try in Firefox and see if I can replicate your issue. Also, if you make any JSON levels, please share them. You will find I posted a latest version at http://lostwords.org/risk/levels.html
Here you will find the latest versions of the game (I made small updates) and some JSON examples. If you open the dev tools tab in your browser you will get the JSON values logged to console. Pressing < , > comma in the game will allow you to paste your own JSON. (A default JSON is provided in the prompt so you can copy that as an example and see what it looks like in a text editor. Any JSON you post in the prompt will comprise the game level so it needs to be valid JSON based on examples and is strict for comma's and things. So if your JSON is good, you'll be playing in your own JSON world.