I’ve just checked this on my Mingle sandbox site and the shortcode inserter button is working okay with WordPress v4.2.2 and Mingle v1.8.3.2. If it’s not working for you then the most likely reason is a JavaScript error caused by a plugin conflict. So to begin troubleshooting this issue you should deactivate all plugins (all at the same time) to make sure the plugins you have installed are not causing any issues. If the problem goes away, reactivate your plugins one at a time (individually, not incrementally) until you find the one responsible. If the problem persists after all plugins are deactivated (all at the same time) let us know and we will work from there.
