4th possibility is corrupted config.txt, way to find that out;
1 Create new route and save.
2. Open content manager, select new route.
3. Open new route for edit in explorer.
4. Select bad route, edit in explorer.
5. Copy all files except config.txt from bad route. Switch to explorer window for new route, paste, yes to overwrites.
Edit, commit. Go back to surveyor, see if the new route will load.
Way to find out if it's a faulty dependency, select bad route, View dependencies, view in main list. First thing is to see if anything has a red ! or yellow or red puzzle piece.