Same problem here. It is not possible to reply from Gmail. Maybe someone solved this?
Uncommented line 8 and 9 in a file panel.js and the icons become visible.
I also want to ask, if someone can help, how to get post content (location post) in marker info bubble.
Same problem here. The map icons are not visible on the map and also in the “add new location” dialog in “Map marker options” section. I edited a file “admin-display-icons.js” with the plugin editor where the source for markers were pointed to http://wpmapmarkers.com/ which is down.
I replaced this with my site address. Now the markers icons are visible in the add new location dialog but still not visible on the map.
Thank you.