Importing Mesh From Blender is transparent (Unreal Engine 5.1)

I have created a mesh of part of a road I intend to use with splines.

All the normals have been recalculated, scaled, etc. (To the best of my knowledge.)

Whenever I import it into Unreal Engine 5.1, it is transparent on one side ( and not the side I want)

If I flip it 90 degrees I can see the material\texture

But if I flip it all the way it goes black.

I have tried two sided materials in Unreal, flipping the normals in Blender, etc, etc to no avail.

Any assistance or guiding direction would be much appreciated :slight_smile: