OnClick() area has empty field when "No Function" selected

2) How can we reproduce it using the example you attached

1 Create new project or use attached
2 Add Menu->GameObject->UI->Button
3 In Hierarchy select the Button
4 Go to Inspector and in Button component find On Click() area
5 And press "+" and select MainCamera as object and function GameObject->"string name"
6 Create cube in Hierarchy and add new CSharp script tp it
7 Now select the Button in Hierarchy and in On Click() area select Cube as object(instead of MainCamera )
Actual result: the function name is "No Function"(as expected), but there is empty field (Not expected) - see attached image

Please see attached video