Why my Terrain is disappearing after saving as Prefab

Just updated my version of Unity to 2018.3.0f2. Pre-date Could just save the terrain. But now, as soon as I create a prefab and try to reload it in. It simply wont appear. It is still an object in the assets folder, but cant modify it.

UPDATE:

Appears the creation of the terrain doesn’t create any Terrain Data?

Had to do with the scrip I was using. I use the Obj2Terrain Script, and just never had this issue before. Had to export height maps and some settings. Create new terrain and import. Solved