here is a screenshot of my problem. As you can see, there is this blue line at the bottom of every city (it is less obvious in the "Faryst" city because I built buildings to hide it a little bit).
Some more details :
=> This issue only happens in region mode, when I enter in the city, it all works fine.
=> I tried to remove every single plugin but I still had this issue. I also tried to re-installed the game but it persisted...
=> First, I thought it was because I imported the map from SC4mapper but this issue occurs with vanilla regions such as "Berlin" for example.
Can someone help me please ?