For testing purposes I increased the Parameter to 100. As you can see, the Landscape itself does not change very much and stays flat, although something seems to be processed (due to the deformed outline)
I had a feeling you were using âCrack Free Displacementâ
What you are reporting is a known and reported issue: UE-38815
Once the issue has been addressed by our engineers the ticket will be updated and reflected in the public tracker. Let me know if you have further questions or need additional assistance.