JSONMarshalled not working in Delphi

I have the following simple class using Delphi XE7

{$M+}
{$RTTI EXPLICIT FIELDS([vcPrivate])}
TEntityForCreation = class
private
  [JSONMarshalled(False)]
  FCreator: Integer;
  FDescription: String;
public
  property Creator: Integer read FCreator write FCreator;
  property Description: String read FDescription write FDescription;
  function ToJsonString: string;
  class function FromJsonString(AJsonString: string): TEntityForCreation;
end;

      

        
        
        
      

    

ToJsonString method uses native JSON serialization

function TEntityForCreation.ToJsonString: string;
begin
  result := TJson.ObjectToJsonString(self);
end;

      

        
        
        
      

    

For some reason, the Creator element is always serialized to a Json string. I have turned on "Emit Runtime Type Information" to "True" in the project options.

While executing the JSON marshalling code, I can see that it simply doesn't recognize that JSONMarshalled is associated with FCreator. I suppose there is some compiler directive missing somewhere, but can't figure it out.