I saw that no one answered this so I have done some tests and apparently if you put a new object with the height more than 0.0 you can´t change it after.
If you put a object with height 0,950 (for example) you will not be able to change that.
If you want to do not have that error you have to put every new object with 0,0 or less.
That´s because you didn´t put all the folders correctly in D:/ Ymir Work or just because you didn´t but correctly the route.
Remember that you only have to put the last folder of every folder like TerrainMap , TextureSet..