Hi all,
Made a few fixes for this update.
There was an error preventing you from adding prefabs to an empty slot. This has been fixed.
There was an error preventing you from removing a type of block or grass. This has been fixed.
The X buttons gray out when you cannot remove anymore land or grass.
The Pine_08 tree was having an issue with a missing shader. This has been fixed.
The scene loader has been updated to use Unity 5.5.0f3
Enjoy!