[2.4.4]Fraticelli pope election "black bishop" not working

[oderis]

Hi,

I'm playing without any mod, I have all DLC except Sunset Invasion.

So I'm playing an ironman game, recreated the fraticelli papacy (which became the dominant sub religion of christianism). I vassalised the pope, and managed to have a wicked cardinal. I then assassinated the pope when i saw that my wicked cardinal was the Preferatus.

However i did not get the achievement once he was elected. Am I missing some critical point concerning the achievement?

 

[King Anund]

Fraticelli papacy doesn't even use Papal investiture for me, even though I have SoA

 

[oderis]

Well that's another kind of bug, I have no more intel about mine, I finally cheesed the achievement in another game but it wasn't with the fraticelli papacy...