did i found some sort of bug with 4.15 ?

hi guys,

I wasnt there before 4.15 i just started using UE4 and now im having issue with AI setting…
Most of the tutorial i find have a method that i would like to use but its not working here is the problem :

1.they ask to create a new AI controller bp and give it a name so i create it , AI_control_bp

2.then they copy the thirdperson character and rename it , so i do the same AI_Character

3.then they ask to open the character editor window and delete the event graph

4.then go into viewport / class default / under detail found pawn and change AI controller class for the one i create in 1. (this is where its not working) i cant change it when i click my bp its
just saying ’ none ’ and not the name of my bb like in the tutorial.

anyone could try to help me if you guys understand the issue…