Abnormal color of visualization

[BuuNguyen]

Dear STKO team

When I show my model in property visualization. there was a dark region as in attached picture.
What possible properties do exist in this region?

Thank for your support.
Buu

[Clarabella]

I think that you need to change to revert the face: reverse face in geometry
Regards

[BuuNguyen]

Yeah, thats true, thank you for your help.