I had been working on a new project which was going along well until I went in and changed the name of three shader layers; then, looking at the preview wind, I noted that the scene went 'dark'. In review of all the settings, The following has changed as a result of some bug: terrain is missing; surfaces 1, 2 and 3 are missing. The only two shaders still there are Fake stones. All other things are still there. Also not that the Node Network shows that everything is still there.
I did go into the Node View and hooked the Compute Terrain to the planet and the heightfields showed up; however, the Shaders are still not showing up. I noted that the Fake stones are not connected to anything. How does this happen?
Attached is the file for your review. Note, I had loaded a .ter terrain which is also missing.