The page above has a tabbed panel with a number of tabs. The Pro Map is on the second tab (tab 1, Location). I've just discovered something strange. If you load the url above and the page loads displaying the first tab as the default tab (tab 0, General Info), the problem occurs. When you click on the Location tab you'll see that the map graphic does not fill the Pro Map window. However, if you force the page to load (using the url below) and initially display the second tab (tab 1, Location), everything looks and functions just fine. Weird.
I suppose to avoid the whole issue I could put the Pro Map on the default loading tab, but I would rather not. In which case, I'm still hoping to resolve the issue.