Checked a couple and can't see anything wrong with them here, can be downloaded in Manage Content if you search on the kuid which I did, no errors or...
If using them on flat terrain the easiest method is to lower one spline point, so the grass is level with the ground surface then set all the others...
Method of use is to lower the ground under the grass plane until the grass is level with the surrounding terrain, done like that to blend seamlessly,...