I'm an independent monarch and I'm currently "bound by truce not to attack" two other kingdoms and in the Notes section it says that "The truce will expire in 20 days." but it's been well over a month and it's still showing 20. One thing I've also realized is that they do not declare war upon me unless I "threaten them with war to see what we can squeeze out of them".
Points that I think may be relevant:
Game was initially started in Static Wars mode.
Static Wars mode was turned off shortly after I founded my own kingdom.
Same happened for me, however, I started in static and switched to sandbox following the Red Wedding. Founded my own kingdom after roughly 500 days.
Were you able to find a fix?