I fabricated a claim. I gained a favor from my liege, requested council support from 3 other council members (in a duchy-level council so we're 4 against 2; I thought in 3v3 the liege would break the tie) and when I try to have my liege press my claim the button is greyed out and the tooltip says that the council won't agree.
Then, I waited a few months to pass by to see if the AI would refresh and allow councilors to vote yes and before something change, my liege declared war for my claim on its own initiative... That's nice but next time I feel like throwing a few thousands coins for a county, I wouldn't mind for it to work (or to know how to make it work). Though I guess that my liege would not have declared war without the agreement of the council so that certainly helped to bribe councilors.
So if anybody has an idea of what happened, I would certainly like to know.
Then, I waited a few months to pass by to see if the AI would refresh and allow councilors to vote yes and before something change, my liege declared war for my claim on its own initiative... That's nice but next time I feel like throwing a few thousands coins for a county, I wouldn't mind for it to work (or to know how to make it work). Though I guess that my liege would not have declared war without the agreement of the council so that certainly helped to bribe councilors.
So if anybody has an idea of what happened, I would certainly like to know.