I recently returned to Emperor after a few years.
But I now encounter a problem which I think is some kind of bug.
In every historical campaign mission I play every rival turns hostile in no-time no matter what I do. I keep sending gifts of what they need, even cash sometimes but I can't keep them from turning hostile. They even kill the emissaries that bring them their gifts.
Sooner or later they will start invading me for no reason. One city even sent me 3 invasions in 3 months. There's nothing I can do against that, certainly not in the missions that don't even allow me to build forts.
I don't remember being attacked in a mission that doesn't allow forts even once when I played the game years ago.

My version is 1.0.1.0
I'm playing on normal difficulty

Is there a solution to this problem?