From the image below, you can see what my bug is.
Basically, I have a river connecting to a lake, and when I save and get out of UEFN and then get back in this happens (An in-game test also had the same result). I can temporarily fix it by moving it in any direction and doing CTRL-Z.
But doing that every time I get on UEFN is a little tedious.
Is there a fix in the details tab or just a bug?
Here’s another example image.