Right so it looks a lot better now, nothing to do in unreal, it was all CC witchery (see edit in previous post) !
https://i.imgur.com/TNP7TBV.png
I was using 32bit floats for the plugin, nothing changed in the source header.
On the LOD subject, every time I try to enter a 0 value on X for the lod curve the engine crashes. So the LOD0 is actually LOD1 ? 
Looks like the mirrored axis is X if I compare the model in UE and CC.