Hi Tim,
Thanks, as I said it was working properly before the latest patched so Im a little confused, Ill try rebuilding the mesh in ArchiCAD>Blender and hopefully I get some luck.
Thanks for explaining the lighting settings too, my actual job in in architecture so Im trying to piece together UE4 from no prior game dev experience hence why my lighting set up makes no sense 
The results are incredible though, game changer for my clients! Ill let you know how I get on with rebuilding the mesh when I get a chance, thanks! Kyle