Ok, so there are two things that you have to consider. The first thing is the requirement which allows you to put the player in the evo. So if your player has 4 Playstyles he is eligible. The second thing is a max cap of playstyles the player can receive through the evolution. The playstyle cap for this evolution is 4. This means that he can't receive the playstyle as a fifth playstyle. While this is not really a bug, the requirement/cap doesn't make sense in this evo. Why would you put a player with 4 playstyles in an evo that doesn't give you a fifth playstyle? Maybe they will change it. Until then, always pay attention to the max cap first before you activate the evolution. Hope this helps :)