I was able to reproduce the issue. This should be addressed in the next hotfix. You should contact the support group and reference issue # 15396 so you can be notified when the hotfix is available.

I am trying to use a ContextMenu on a ListView in a ToolHorizontalWrapPanel.  I tried setting the ContextMenu directly on the Ribbon Tool, (which sounds like the original problem) but that didn't work either.  The only way I could get it to pop my menu instead of the Ribbon's was to use PreviewMouseRightButtonDown to handle the event.

<igRibbon:ToolHorizontalWrapPanel>
    <ListView x:Name="ErrorMessagesView"
          ScrollViewer.HorizontalScrollBarVisibility="Disabled"
          Background="{Binding Path=Background, ElementName=xamRibbon, Mode=Default}"
          BorderThickness="0"
          ToolTipService.ShowDuration="30000"
          MinWidth="400" PreviewMouseRightButtonDown="ErrorMessagesView_MouseRightButtonDown"
          MaxWidth="800">
        <ListView.ItemContainerStyle>
            <Style TargetType="ListViewItem">
                <Setter Property="VerticalContentAlignment" Value="Top" />
                <Setter Property="MinHeight" Value="20" />
            </Style>
        </ListView.ItemContainerStyle>
        <ListView.ContextMenu>
            <ContextMenu>
                <MenuItem  Header="Copy to Clipboard" Click="MenuItem_Click"/>
            </ContextMenu>
        </ListView.ContextMenu>

I believe the issue that discussed at the top was addressed so if you're still seeing an issue perhaps you have a different issue. I would recommend submitting a sample project to the support group that demonstrates the issue so we can look into it. Also, if you can post the sample here so I can see what you mean.

Its easy enough to hack around this with MouseRightButtonDown on your menu'd control and just set ContextMenu.IsOpen = true from code behind. 

Has this been fixed?  I just ried 8.2.20082.1002 and no joy.

tia

-Kurt