The map looks and works fine at first, but when I zoom in or scroll around a few times, the map disappears and the markers remain. The markers still work, but there’s no context. I have entered one Google Maps API on 10 subdomains, each of which has about 7 maps.
This appears to be a bug with Google maps, can you please go to your settings (Maps -> Settings) and change your API version to a more recent version firstly?
If that fails, I discovered that resizing the window brings back the background, it’s not an ideal solution but you can use the following custom JS to fire a resize event causing the map to redraw itself