Xamarin.Forms 2.0 WinRT Scrollview not scrolling

I have a ScrollView thus:

      <ScrollView VerticalOptions="FillAndExpand" x:Name="ScrollTestEntry" BackgroundColor="Red" Orientation="Vertical" >

        <Grid x:Name="TestEntryArea" VerticalOptions="Start" RowSpacing="10" Padding="30,10,30,0">
          <Grid.ColumnDefinitions>
            <ColumnDefinition Width="3*"/>
            <ColumnDefinition Width="7*"/>
          </Grid.ColumnDefinitions>
        </Grid>

      </ScrollView>

The "TestEntryArea" Grid internally is filled at runtime programmatically.

The ScrollView ends up being 232 pixels in height and the Grid ends up being 275+ pixels in height. The content is visibly clipped but it refuses to scroll.

Anyone seen this before? I have tried lots of layout changes (StackPanel, InputTransparent = True on sub controls etc) but this scroll view will not budge.

Any help appreciated!