Getting the same thing here. The issue appears to be caused when users (from what happened to me and others on here) reinstall the plug-in, either by choice or via an update (what happened to me), when on 6.7.0
The plugin worked for me before and after the upgrade from 6.6.1 to 6.7.0 however failed to work after it prompted me there was an update available (the 05.02.2019 update) for it and I went through the update, causing it to reinstall.
Tried reinstalling the plugin from CA and from the link provided by the developer at the top of this thread. Also tried rebooting my server.
No luck after either. only shows up in the location shown above, nothing under settings and when i click on the icon for the plugin on the above screen, it brings me to a blank page.