NullReferenceException with {x:Bind} inside generated code

[Palatis]

I'm trying to set a EqualsStateTrigger in a VisualState.StateTriggers with the following code:

<VisualState>
    <VisualState.StateTriggers>
        <triggers:EqualsStateTrigger Value="{x:Bind NavView.IsPaneOpen, Mode=OneWay}" EqualTo="True"/>
    </VisualState.StateTriggers>
    <VisualState.Setters>
        <Setter Target="HorizontalAlignment" Value="Left"/>
    </VisualState.Setters>
</VisualState>

as taken from the example (https://github.com/dotMorten/WindowsStateTriggers/blob/master/src/TestApp/Samples/EqualsSample.xaml)

however it throws NullReferenceException during InitializeComponents().

====== Investigation... ======

digging into generated code (MainPage.g.cs), it calls

public static void Set_WindowsStateTriggers_EqualsStateTrigger_Value(global::WindowsStateTriggers.EqualsStateTrigger obj, global::System.Object value, string targetNullValue)
{
    if (value == null && targetNullValue != null)
    {
        value = (global::System.Object) global::Windows.UI.Xaml.Markup.XamlBindingHelper.ConvertValue(typeof(global::System.Object), targetNullValue);
    }
    obj.Value = value;
}

where obj == null...

I also dug into public void Connect(int connectionId, global::System.Object target) , seems it doesn't call Connect with the IDs for my EqualsStateTriggers:

case 9: // Pages\MainPage.xaml line 138
    this.obj9 = (global::WindowsStateTriggers.EqualsStateTrigger)target;
    break;
case 10: // Pages\MainPage.xaml line 126
    this.obj10 = (global::WindowsStateTriggers.EqualsStateTrigger)target;
    break;

before calling

XamlBindingSetters.Set_WindowsStateTriggers_EqualsStateTrigger_Value(this.obj9, obj, null);

My stack:

MyApp.exe!MyApp.Pages.MainPage.XamlBindingSetters.Set_WindowsStateTriggers_EqualsStateTrigger_Value(WindowsStateTriggers.EqualsStateTrigger obj, object value, string targetNullValue)
MyApp.exe!MyApp.Pages.MainPage.MainPage_obj1_Bindings.Update_NavView_IsPaneOpen(bool obj, int phase)
MyApp.exe!MyApp.Pages.MainPage.MainPage_obj1_Bindings.Update_NavView(Microsoft.UI.Xaml.Controls.NavigationView obj, int phase)
MyApp.exe!MyApp.Pages.MainPage.MainPage_obj1_Bindings.Update_(MyApp.Pages.MainPage obj, int phase)
MyApp.exe!MyApp.Pages.MainPage.MainPage_obj1_Bindings.Update()
MyApp.exe!MyApp.Pages.MainPage.MainPage_obj1_Bindings.Initialize()
MyApp.exe!MyApp.Pages.MainPage.MainPage_obj1_Bindings.Loading(Windows.UI.Xaml.FrameworkElement src, object data)

I'm targeting Windows 10, version 1903 (10.0 build 18362) (both target and minimum).