What is going wrong with these normals?

These walls all have the same material applied. The light is coming from above and behind the camera.
The normal map should make the bricks appear to protrude past the mortar but if you see the screenshot:
the red walls are correct,
the green wall seems to have the y channel flipped,
and the blue wall seems to have both x and y flipped.
The vertex normals are correct both in Blender and Unreal and the model is correctly uv unwrapped to use a tiling texture.
What have I done wrong here?

Show us the material graph and maybe the normal itself ? Not enough info to help you sorry