Google Map integration problem

On the event page, the Google Map seems to work fine. However, on the front page where I have added the event with a shortcode I get an error - "Oops! Something went wrong.
This page didn't load Google Maps correctly. See the JavaScript console for technical details."

I have double checked the Google API and tried various options however I can't seem to get it to work. Any advice would be appreciated.

Main page with problem:

Event page where all is well: