I declared war on purple as they fought orange in order to catch them off guard. Purple ended up vassalizing orange after their war, and while they were still fighting me in a separate war. I thought that these new territories would be easy pickings for my army, but I was not allowed to enter them. It said I lacked the war support. The diplomacy screen still shows us at war, so I think some flags were triggered, but not all of them. An additional side effect is that my vassal who was raiding orange's territory at the time is constantly racking up grievances for trespassing, and orange is racking up grievances for oppressing my people and religious practitioners. This side effect will essentially create a total war, as their war support fills up faster than I can drain it with crushing defeats, making me siege each of their cities.

20210613225504_1.jpg Can't enter the vassal of my enemy's territory

20210613225522_1.jpg War with Orange, kind of?

20210613225511_1.jpg Grievances