We are working with a custom theme however we received the same JSONP error when switching to the default WordPress 2014 and 2015 themes.
I currently have the SLP cities widget setup in the global sidebar on its own. I also had it setup independently in the page sidebar yesterday, but was getting the same error. I’ve included a screenshot for you of the widget setup.
The url is the same as in my previous screenshot. http://www.ninthfloor.ca/client/nwtestmap/dealers