From the beginning I am trying to use your plugin, I have the same problem about map displaying.
I am on Mac. It works with Safari (6.01), but never with Firefox (17.0.1).
With Firefox, I get the pins but never the map.
It was the same with previous version of Firefox.
Researching about version of BingMap the plugin use, it seems to be :
Bing Maps AJAX Control, Version 6.3
According to Bing Maps AJAX Control Troubleshooting and Support
It seems that Firefox is supported for PC, they don't mention Mac.
Could this be the problem ?
If this is the problem, have you tried to implement Version 7 of BingMap, instead of 6.3 ?
Version 7 is said to support BingMap with Firefox for Macs and PCs ?
Thanks for your answer.