The first image shown below is of part of my mesh in Blender, and the second is of that same part of the mesh in UE4. For whatever reason, the UVs are distorted and glitchy once imported into UE4. I've tried flipping normals, made sure no UVs are overlapping, re-importing the mesh in a bunch of different ways, and turning on full precision UVs, but nothing seems to fix it. If anybody knows how to fix this, please let me know. Thanks! :)
Blender and unreal engine read the meshes in a different way, I don't know the geometry of your object, but sometimes when you have n-gons, sometimes even quads, blender triangulates the mesh in a different way from unreal causing this artifacts in the UV channel. You can fix it using a triangulate modifier on blender, in this way you tell precisely how to read the mesh to unreal.