Maybe your firewall (its not allowed for urwigo to access to the internet), turn it off for a few seconds, to check.
In my case i have to create a rule in the firewall for the application "C:\Users\jonny\AppData\Local\Apps\2.0\A1ECLB9B.DPH\H3CPYRJB.X4R\urwi..tion_05d1297f39f02515_0001.000c_3dd93d5035c5b17f\Urwigo.exe"
If i turn the rule off, i have the same as you, an empty map.
I've run into the same problem as the above poster: maps worked fine for weeks then suddenly stopped two days ago. Sometimes I get an error message - 'The Google Maps API server rejected your request. The "sensor" parameter specified in the request must be set to either "true" or "false".' - and sometimes I just get a blank map. I tried changing my firewall settings without any luck. The sudden onset makes me wonder if it's somehow related to an update (Java?).