Since so few people play the late game, I'll explain. Some of the later techs allow you to push all claims you have simultaneously. In this case, I pushed a claim as the kingdom of Frisia, against the kingdom of Germany for all de jure land. Despite choosing that Casus Beli, I was only claiming one county. I seized down that county, yet Germany was receiving a ticking war score since I "didn't control the war target" Is there something I'm missing, or is this a bug? One other thing to note is this is an ironman save with no mods.