DisplayMemberPath not work when ComboBox items binded to DependencyObject

[ACGNnsj]

Describe the bug

The text of dropdown menu is empty.

Steps to reproduce the bug

Here's the definitions of binded items.
LanguageItem.idl LanguageItem.h LanguageItem.cpp
The items have been used here.
ConfigPage.xaml ConfigPage.xaml.cpp

Expected behavior

The properties setted in DisplayMemberPath displayed properly

Screenshots

These outputs seem to be common exceptions of some controls.

NuGet package version

WinUI 3 - Windows App SDK 1.3.1: 1.3.230502000

Windows version

Windows Insider Build (xxxxx)

Additional context

No response

[ACGNnsj]

I misused Items instead of ItemsSource.