WPF Combobox is setting the new object's value on the old object when selecteditem is changed via datacontext

I have a ComboBox in WPF. The ComboBox is inside of a grid, and the grid's DataContext is bound to the SelectedItem of a ListView. The ItemsSource of the ComboBox is set to a StaticResource, located in the window resources. The ItemsSource does not change. I have tried to use both SelectedValue and SelectedItem but both of them cause the same issue for me. The issue is that when the SelectedItem of the ListView is changed, the ComboBox is actually setting the property value from the PREVIOUSLY selected item, to the property value of the NEWLY selected item. Clearly I am doing something wrong, because I have used comboboxes many times in the past without this issue. I have scoured the web and can't find an answer. The closest, most similar question I found was: Strange behaviour (or bug?) with ComboBox in WPF when changing DataContext and having bound ItemsSource and SelectedItem

But it doesn't seem to have a solution. The solutions listed in comments did not work for me.

I created SelectionChanged events for both the ListView and the ComboBox and set breakpoints at each of them and the property that is being set. The property is actually being set BEFORE either one of those are triggered. So even if I wanted to create some hack workaround, I couldn't.

For the record, the ComboBox functionality works perfectly fine. When an object is selected in the ListView, I can see the Template name property, as I should, and the list of items is correct. If I manually change the selected item, the property is changed to a new item, just like it should. The problem is that when I change the selected item in the ListView, the "Template" property of the newly selected object is being set to the "Template" property of the previously selected object. So the combobox is changing before anything else.

The xaml for the ListView and ComboBox are below.

<ListView x:Name="my_ListBox" FlowDirection="RightToLeft"
      Margin="5" Grid.RowSpan="2" SelectedIndex="0"
      ItemsSource="{Binding Source={StaticResource myList}}" 
      DisplayMemberPath="Name"
      SelectionChanged="my_ListBox_SelectionChanged"/>

<Grid DataContext="{Binding ElementName=my_ListBox, Path=SelectedItem}">
     <ComboBox Name="comboBox_myTemplate"                                       
               ItemsSource="{Binding Source={StaticResource myTemplatesList}}" 
               SelectedValue="{Binding Template}"
               SelectionChanged="comboBox_myTemplate_SelectionChanged"
               DisplayMemberPath="Name" FontSize="20" Margin="5"/>
</Grid>