Can not select new rivals

[Didymus]

Hello,

as the title says, i can not select new rivals. I chosed bohemia as a rival in 1444, as they did, and now, 100 years later Bohemia stopped seeing me as an rival. Because i am a nice person, I wanted to remove my rivalry too.
But the buttons for new rivals are grey...
At this moment I was not at war and had the 100 diplo points.
My only guess is, that I can not change, because I am the leader of the catholic league...

Playing on 1.23.1, because I fear the new patch will break my saves.

 

[pfcpointer]

Are you aware that if you already have 3 VALID rivals, & want to remove one that you have had for more than 25 years, then you have to physically remove it by right clickiing on its shield (paying the 100 diplo mana cost) BEFORE being able to select a new one?