Apparently, somewhere between WP 3.7 and 3.8, or even a bit earlier, this plugin stopped working.
There isn't much to describe or note. If you are using the plugin and the version is higher than 3.9.5, it won't work. Period. Until the author of the plugin decides to fix it, there is nothing we can do.
If you want to resolve the problem, please email me, and I will send you version 3.9.5 via [ email and link redacted ]
Great plugin. Too bad the support isn't available at the moment.