Terrain "set height" cannot read height

I have some strange terrain effects in Unity 2019.1.14f

There is a terrain that’s almost flat. The basic transform is somewhere at y=-1006. All effects can be seen on the flat areas as well on the hilled areas. The terrain basically was created moth ago with a lower Unity version.

  1. I cannot get a base value for set height. There is no value taken.with Shift - Left Mouse.
  2. I can enter any value for height in set height, the result is always the same height.
  3. The value for Opacity seems to control the height.
  4. On some textures my chars (having a rigidbody) sinking into the ground a little but sufficient to have the feet below the surface.

What I found eventually:

The terrain y values must be in world coordinates in the range of 0-max height. This was different in older Unity versions.

You can move a terrain to other y ranges, but then strange effects might occure and editing the terrain might become impossible.

Applying the terrain to another gameobject as child and moving the parent object while the terrain itself is zero’d has the same effect as if you change the transform of the terrain itself.

If you want to have multiple not connected terrains out of view in a single scene, you have to move it in x and z direction but keep the y direction.