Either I've missed a stage out in the process or I've simply misunderstood something.
I create a material for a floor surface and then create a simple box primitive shaped at 300x300x50.
I drop the material onto the box and go to faces and centre it so it fits nicely. From the scene I then right click and save as a prefab.
When I drag from the prefab folder into the scene the texture is as I expect, but if I move the object in the scene the texture jumps to a random offset so that I have to go back into the face editor and re-orientate it again.
Is there any way to ensure the texture stays pinned as saved?