It actually flickers between visible and invisible, and also seems to be slightly below where I originally left it.
I don't get the problem at all if I just leave it alone and don't set the motion type, however I need it to stay in the same place.
Has anyone else come across a problem like this before?
Note:
I have tried saving the XYZ positions and then setting them when the object Loads again, and for testing I set the Z to +20. If was floating above the ground (as you'd expect) but flickering.