I didn't do anything special before I got that most impressive, if harmless bug.
Note that if I click on one of them, I get a “your target is obscured”, and when I point to one, like on the screen, there is a ghost image of the mold in the map area.
If I try to leave the zone from here, the it behaves like the border of the map was a wall.
A save/reload solved the problem. It may be more annoying to those who chose not to be able to save when enemies are near, I suppose.
Edit: And while I'm at it, did you know there was a standard game saves folder in windows? It makes finding them so much easier, and keeping them even more when you reinstall windows… Why half the game devs don't use it is a mystery to me.
