Brandenburg still Support Independence of Vassal during a Truce

[CannedBison]

Either I'm not fully understanding the mechanic or I have hit upon a bug in the game.

Playing as Mulhouse, I have accumulated several OPM vassals in the HRE during my expansion with the goal of annexing them eventually but Brandenburg began supporting the independence of some, raising liberty desire of Frankfurt and others which makes the plan harder. So I declared a war on Brandenburg, won and got a peace deal.

My understanding from other posts and wiki is that either (1) fighting a war or (2) securing any peace deal with a truce would end Brandenburg's support for my vassal's independence, but neither happened and Brandenburg continues to support and raise the vassals Liberty Desire. I have both restarted the game and also let a month pass to 'refresh' relationships if either is necessary, but now I'm stumped. Did I miss something?

[grotaclas]

A truce between you and the supporter prevents a nation from starting to support the independence of your subject, but it doesn't end the support. You need to get your subject into a war with the supporter to end the support(so they must not be scutaged). Does the wiki say otherwise?

[CannedBison]

That is the missing piece indeed. Yes, I have all my vassals on scutage so that being in a war wouldn't prevent them being annexed later if the vassal was in a war. The other sources weren't clear about the vassal needing to be a participant in the war against their independence supporter as well, so I suppose that's the answer then.

[D-Black Catto]

scutage sounds like something dirty and sexual. I have never forced my vasals to do such a thing.