Sorry for the delay, I had some problems to reproduce it.
But in fact, you have the same thing on your demo site.
The problem is the same when you try to print or send an email.
It begins when you select "Show hotspots from all categories"
If you try to print you have the message "Transferring data from maps.google.com..." and no map shown.
If you have a category icon on the right side, click on it. And if you try to print this map, the category icons are replaced with the world (all categories) icon.
If you click a category icon on the top of the map, everything works (again) perfect.
Best regards.