Mesh Differences - blender vs UE4


I’m having a weird issue with some of my meshes that have been generated by photogrammetry.If I import them into blender and activate the lookdev view then they appear fine. When I import the exact same meshes into UE4 editor I get various glitches - see attached files for example. They also display fine in the Windows 10 3D viewer.

The files were originally output from 3DF Zephyr Lite and are fbx files with four materials, each with its own texture applied. UE4 complains about overlapping UVs of 4% on the mesh I’ve attached images on but I don’t know if this has anything to do with the errors.

If anybody has any idea how I might be able to fix these meshes so they display properly in UE4 I would appreciate it.