Not sure how it's with JEM 2.x but noticed with JEM 3.0.7 that there is a problem with loading Google map. It needs an Api-key. Guess the problem is with JEM 2.x too? Am currently not running JEM2.x so not sure, just wanted to point out that there seems to be a problem.
Google Maps Platform rejected your request. You must use an API key to authenticate each request to Google Maps Platform APIs. For additional information, please refer to
JEM2.x is the active development path, JEM3.x is not supported (obsolete)
I can confirm that you will need api-key to display Google Maps in JEM. This is something that the person setting up JEM on their website must do, if they decide to use Google Maps, as there are quotas involved on number of api calls, both total and frequency.
Also, there is a extra parameter in JEM maps service that is no longer required and can be removed (sensor).
Also, if JEM knows that Display Google Maps is selected and user has not entered api-key then JEM should not output Google map as it will error (shows as blank area with errors on browser console).