LOD bug imported morph targets on metahuman

Ive imported a head from blender and replaced the face mesh, everything looks good close up but when you zoom back and the next LOD kicks in it switches to the old face mesh lod and so the face completely changes back to the original, any ideas please ? P.S ive regenreated the LODs in the mesh but it still goes back to the original mesh from LOD 01 onwards and only LOD0 is correct