Hi! Please try this:
[FBX Import Settings (Static Mesh)]
//In the import dialog
1. Normal Import Method
• Import Normals and Tangents (preferred if authored correctly)
OR
• Compute Normals (UE recalculates smoothing)
2. Advanced -> Normal Generation Method
• MikkTSpace (default, correct)
• Reimport after changing settings.
If it doesn't fix the issue, please send me a message on Discord, or an email, and we will get it sorted!