Some triangles are darker than others.

I’m having some trouble with the shading of some of my meshes in unreal engine. Some triangles appear darker than others, like there is ambient occlusion on random triangles.

[First one is in Unreal Engine with the shading issues (note the lighter triangles on the bottom front of the mesh. Second one is in Substance painter without any shading issues whatsoever.][1]
[1]: Imgur: The magic of the Internet

Any ideas? This is baked from a high poly mesh without shading issues.

Update:
The issue only occurs on skeletal meshes but I can’t seem to get rid of it. On a regular mesh the shading works perfectly.

Now I know the issue was with it being a skeletal mesh I could search more specifically for an answer.

“Thanks to user HenrikRyosa from the
UnrealEngine forum. The fix was to
import with normals and tangents under
the Normal import method on the
Mesh section of the import window.”

Source: