Another aspect of exporting from Blender to UE4 is the axes (XYZ). They’re different in Blender from UE4. I think -Y or Y needs to be changed to +Z (Z up) before export, and the other axis to X. It’s the last two that need changing in Blender when in export settings. Otherwise, UVs and mesh faces / vertices are going to be facing the wrong directions in UE4.