What’s Wrong?
Open up some materials and re-save them. Make sure no texture references are missing. If a roughness texture is black or roughness input is missing, I could see this happening.
Resaving does not help, also material become unshiny only when Roughness is 1.0
Also, I noticed, if decal turned off, everything seems to become normal, but when I start the game everything are become glossy again=( Sorry for my english=(
If you make a new default material, does it still appear super shiny with Roughness at 0.5 or 0.99. When roughness is 1.0 for the whole material, it makes sense that it makes a more optimized shader path similar to the “Fully Rough” setting. But 0.99 should be indistinguishable from 1.0. I am wondering if something about your normal maps is messed up?
Interesting clue regarding the decal check box. Do you have any decals in your scene? I could see a scenario in which a big decal is overriding all roughness values within it, but your material editor viewport seems to be showing the same issue.
What engine version is this?
Engine version is 5.4.3
here is how new material is look like
No, I have no decals in my scene and the same scene was normal on version 5.3.1
In 5.5 this problem still persists. I find it strange that almost no one mentions it. It seems that very few users have encountered this problem.
(post deleted by author)
Edit: It fixed 1 project but it didn’t fix another project… Still looking for a solution.
Original post: Found a fix for Unreal Engine 5.6.1: The roughness was behaving like a binary value—it was either completely glossy (Roughness = 0.0) or completely rough (Roughness = 1.0), with no change in between (0.5, 0.3, 0.xxx, etc.). Go to the Project Settings and check “Allow Static Lighting.” If you then restart the engine, it will recompile all shaders and the roughness should now work.
Ok, I think I found solution that works. In Project Setting go to Rendering → Misc Lighting and turn OFF DBuffer Decals.