I have the mouse zoom problem, only with a second map window. And also doesn't work at all with firefox.
I have a main map window in a xaml page. zoom in/out works fine with the mouse. I then have a button which opens a child window which allows some geocoding searching, a datagrid with the results, and another map windows displaying the selected geocode location. the mouse zoom doesn't work in this case.
<Telerik_Windows_Controls:RadMap Grid.Row="2" Name="GeocodeMap" IsMouseWheelZoomEnabled="True"/>
public partial class GeocodePage : ChildWindow