Wrong shadowing / no shading with the Displacement

Hello, sorry for such a noob question. I can’t get of how the tesselation/displacement shadowing work in UE4. I used regular displacement workflow and I get weird results. Firstly no shading and no self shadowing without a normal map, secondly my tesselated and displaced geometry is not casing proper shadows, it uses original before displacement to cast a shadow.
I ckecked youtube videos , and wondered other people don’t have displacement shadowing problem - looks like their geometries cast the proper shadows somehow.
I use UE4.24.3 version, ray-traced mode on
Thank you