Random transparency on mesh

Hi, I’m getting random parts of some of my meshes rendering as transparent in UE4. Checked the normals in Maya and they’re fine, all the right materials are applied and tried double sided geometry. I can’t figure out why this would be happening? The UVs are fine too, no issues with the meshes in Maya, it’s only in UE4 that some quads are rendering transparant.

Any ideas how to fix this or what could be the cause? Thanks