Datasmith Megascans workflow


Im using Megascans Atlas grass in Unreal Engine, using 3ds Max to cut out plane and turn into 3d asset. When I export the grass 3ds assets from Max to Ue4 using Datasmith all the meshes import into Ue4 with incorrect axis. All the grass is horizontal, lies sideways instead of upright.

When I export from Max using normal fbx workflow ( Ie not using Datasmith), the meshes import into Ue4 all correctly and stand vertically. Anybody know where I,m going wrong? Any help would be great, thanks.