Nothing exported, nothing really done. Created terrain, added brushes, painting a few square meters and placing down a player. Saved, reloading, tested.
The sometime shortly afterwards when restarted the editor, or after reloading the map, the terrain becomes locked.
I uploaded one of the maps where it happened (have quite a few if it is needed). As you can see, I did not get far, but what exactly triggers is, whether it is saving, reloading or something else, I do not know, but it is something very basic.
Link to bugged map
