Why does the algorithm in the game not change after the change in Visual studio 2017?

Question

unreal engine

Good afternoon!
I study Unreal Engine by book. There's an example
Create an application of the Puzzle type and fix the processing of a click on a square in it.
When clicked, the square turns yellow and the player's score increases.
According to the book, you need to process a repeated click and paint it in the original (green color ..)
I added a piece of code (see screenshot) and that's what you need next - assemble the solution / rebuild the solution / build a puzzle / rebuild the Puzzle. Not written in the book. And accordingly, this Puzzle works for me as before without changes.