Duplicate of UE-11542
When changing the Texture Quality settings through the Engine Scalability settings within the main viewport, the topography/height map of the landscape changes.
The user mentions he originally imported the heightmap from World Machine and were using World Composition. He also found a workaround was to copy the landscape to a new blank map, and then everything worked normally.
The user provided a project with an example landscape displaying the issue. I uploaded and shared this on my drive under the name "LandscapeTopo.zip"
1. Download zipped project from drive.
2. Launch the Uproject file.
3. Change the Texture Quality from Epic to Low/Medium through the Engine Scalability Settings.
4. Notice how when toggling between Epic and Low/Medium quality the physical topography of the Landscape changes.
Head over to the existingAnswerHub thread and let us know what's up.