VsVim - vit and vat not working correctly

Question

I am using the VsVim plugin with Visual Studio 2017. I do a lot of XAML/HTML editing and recently read that the vit / vat commands can select content between tags. However, when the tag definition extends over multiple lines, this does not seem to work.

<Grid x:Name="MyGrid"
      Width="10"
      Height="10"
      HorizontalAlignment="Stretch"
      VerticalAlignment="Stretch">
...
...
...
</Grid> <!-- vit/vat will not work for me here -->

Any insight on how to do this properly? I may not even be using the right commands for this task.