Issue with Pom Silhouette Shader from UE4 Content example

I just tried the Pom Silhouette Shader from the UE4 content examples and run into some kind of weird issue.
The Shader works great, it gives a nice silhouette and the performance is also top but for some reason, height values higher than 0.01 “which is not a lot” breaks something in the shader and a dark shadow starts flying over me, no matter where i move in the editor or game mode. Reducing the height to 0.01 which shows barely the effect of pom makes the shadow go away. Any ideas what could cause the problem ?