4.26 Issue still persists. Displacement Maps are not working. Ensured the Map is having Compression Setting VectorDisplacementMap, sRGB off, hooked up to material node World Displacement and next to it NormalMap to Normal… same as all Material Setups.
Took the Textures Export from Mixer right into UE4.
Tesselation enabled (Flat, also tested with PN Triangles)
The Preview Mesh is however flat. Mesh was a Cube.
In Mixer I am seeing the Displacement clearly, in UE4 is not visible at all. Checked in Wireframe, everything flat.