I built a fishing hut near the edge of the map next to a shoal of fish in a small pond. Next to the small pond was a slightly smaller pond connected by a small strip of water. At first I did not notice, but people were dying of starvation on that strip of land. I thought it was a weird way of looking for something to do, because these starving villagers always had the status of Wandering - unable to work. I then figured they were people being assigned to the fishing hut, so I tested that theory and sure enough, a person went to the fishing hut, went to get supplies for the fishing hut, got trapped on the land piece, and died of starvation. I ordered the hut to be moved to a new location, and 3 more people were trapped. I tried building a road across, it stated there was water in the way and it was an invalid location. I tried ordering them to flatten the land, they did, which slightly lowered the square they were on, but did not allow them to move.
Some rats came around and they were able to enter and exit the square of 10 corpses. I wouldn’t expect rats to have the same pathing as villagers, but I want to be verbose in my description.
Save and Map file
https://drive.google.com/file/d/1GUZyZCQP9DjwfK-j_15rUjsb9-Yx039Z/view?usp=sharing
Screenshots
https://drive.google.com/file/d/1tH9vmcYYBWS43xCleyuWK4hiRT0HVK0w/view?usp=sharing