Bindingsource not assigned

### Environment

Visual Studio 2022 - 17.5.3

### .NET version

7.0

### Did this work in a previous version of Visual Studio and/or previous .NET release?

Yes

### Issue description

Assigning a class as data source to a binding source doesn't seems to work within the designer. The data source class can be selected but isn't assigned as data source.

see attached sample project and screenshots
[WinFormsAppTestBindingSource.zip](https://github.com/dotnet/winforms/files/11086587/WinFormsAppTestBindingSource.zip)

### Steps to reproduce

- Create a new winform
- drop / drop a bindingsource to the form
- create a simple class with one property / member
- open datasource of the bindingsource property and assign the class with "Add new object data source"
- select the simple class and press ok

- expected: the class is assigned as data source
- current behaviour: the class isn't assigned

### Diagnostics

_No response_