Properties of widget slot not visible on editor?

Similar to the UNamedSlot, I created my own slots in c++ with specific purposes. These custom slots hold values like:

UPROPERTY(EditAnyWhere, BlueprintReadOnly, Category = "Setup")
  bool bSomeProperty = false;

I then Add the slot to a UserWidget and add this UserWidget to another UserWidget, like this:


When I click on that slot I can only see the properties of its parent UserWidget.

But I want to see and edit the properties of the slot! Why is this not happening?