I think there is a little confusion here. In my experience:
If you end your mission in a GV on the grass/trees and an enemy is close, you don't get a Ditch, you get Killed.
If you end your GV mission on the grass/trees at a friendly base and no enemies nearby, you will get a Successful Landing.
If you end your GV mission on the grass/trees a long ways from anything and no enemies, you will get a Successful Landing. This is true even if you are three sectors deep in enemy territory. Note, you have to drive away from any enemy base for this to work. I don't know exactly how far, but I've done it a few times when the base I was defending got captured and there was no hope of re-taking it.
If you end your A/C mission on the grass/trees a long ways from anything and no enemies, but in enemy territory, you will get a Captured.
If you end your A/C mission on the grass/trees in friendly territory, you will get a Ditch.
In a GV right next to the map room on the concrete, you should get a Successful Landing. However this is bugged, many times I have gotten a Ditch. I believe this is the bug being complained about here. Any time a GV is on concrete at a friendly Base or Town, you should get a Successful Landing, but frequently we get a Ditch !