Missing properties in PropertyGrid when "Categorized" option chosen for expandable objects (net7.0-windows only)

[bretthysuik]

When an application is built using net7.0-windows target framework, only a single property is displayed for expandable objects when the "Categorized" option is chosen. All properties are correctly displayed when the "Alphabetical" option is chosen.

Everything works correctly when the application is built using net6.0-windows.

Repository that reproduces the problem: https://github.com/bretthysuik/WpfExtendedToolkitDemo