Hello,

Could you please attach a small project reproducing the issue?
I tried with the following xaml, and pressing the Tab key correctly moves the focus between the different buttons and text boxes without crashing Unity.

<Grid
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
  <Grid.Resources>
    <GradientStopCollection x:Key="list">
      <GradientStop Offset="0" Color="Red"/>
      <GradientStop Offset="0.5" Color="Green"/>
      <GradientStop Offset="1" Color="Blue"/>
    </GradientStopCollection>
    <DataTemplate x:Key="dt">
      <DockPanel>
        <Rectangle Width="20" Height="20" DockPanel.Dock="Left">
          <Rectangle.Fill>
            <SolidColorBrush Color="{Binding Color}"/>
          </Rectangle.Fill>
        </Rectangle>
        <TextBox Margin="5,0,0,0"/>
      </DockPanel>
    </DataTemplate>
  </Grid.Resources>
  <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center" Width="400">
    <Button Content="Button"/>
    <TextBox Text="Hello" Margin="0,10"/>
    <ItemsControl ItemsSource="{StaticResource list}" ItemTemplate="{StaticResource dt}" Height="100"/>
    <Button Content="Below" Margin="0,10"/>
  </StackPanel>
</Grid>