If you go with the default settings on WB 4.0, it may tend to do this. There is a lot to play with and you should experiment with it. Nothing stops you form just making random maps in the map section to see if you are getting setting you like or If you use the other world builder you may have more luck.
This thread talks to it some:
https://steamcommunity.com/app/742700/discussions/0/1489992713686401243/