I don’t know if this is the correct category but yesterday I installed the SDK for editing EDSP. Now I don’t have any taxiways and Runways for example in EDDF. I don’t knowe what i’ve done 
Has somebody an Idea how I can fix that?
Enable Draw on terrain in Dev mode → Options → Terrain.
thank you. That worked. But when I disable Dev mode the runways disapear again.
Did you try to restart game after disabling dev mode?
thank you very much