DX12/VULKAN RHI - NANITE - No Displacement

with dx12 the meshes disappear, or if i rebuild they show and have no displacement even though i can see and change the nodes. nothing happens. With vulkan i see all the material instances appear for 1 second then disappear( if i also turn on substrate with vulkan. compiles shaders, then UE closes. no msg) can I only use substrate with dx12? if i use target rhi dx12 and the global illumination lumen. after few seconds or minutes. blank project. out of memory. UE closes. so cant use lumen with dx12 because editor just instantly crashes out of memory. if i dont use dx12 i use vulkan. same result except even more limitation because no substrate. so no dx12 and no vulkan. cant use dx11 because then no lumen/nanite. whats the point. ive spent the last 2 days making no progress because the story of my life is “compiling shaders”

what the…

★ PC Specs ★

CPU: Ryzen 5600x 4600Mhz
COOLING: Aorus 240 LCD AIO
GPU: Gigabyte 6600xt 2600Mhz
RAM: Aorus 32GB 3600Mhz
MB: Aorus x570s (f6d)
HID: Basilisk V2
HID: Steel Series Cherry MX
SYSTEM: Linux Nobara 39
SYSEM: Win10 20H2 (1904)

Someone mentioned that you need DirectX 12 Ultimate . which I also just installed dx packages for this version of win10. but even still.
nanite and lumen work and if i open a project say the megascans complete project
RURAL AUSTRALIA. there is tesselation on the landscape.
but adjusting it does nothing. its either ON or OFF. thats it.

what is going on. wasting days on this crap and no progress at all.