Topic starter is correct. There is a bug here.
I had a buss line that worked. So I continued building elsewhere on the map. Then I noticed that line was loosing money so I whent back and as the topic starter said all busses where standing still at one stop saying “No Path”.
As I said I been working elsewhere on the map.
The route was working.
The only thing that could have “destroyed” the route is the automatic upgrade / transformation of the city. Adding of roads. upgrading buildings etc. It could be a buss stop being destroyed by this process.
What is strange is that the game logic understands there “is no path”. But when the game destroyed the path it did not know what it was doing otherwise it could have reevaluate the path and picked a new path.
Seems some parts of the game is not “communicating” with eachother.