Phantom trains derailed on edge of map

Upon re-entering several different saved sessions in different routes, I find that some of the trains that were sitting/running on the route the day before have disappeared from their original locations, and that they have been 'teleported' to the edge of the route, in
map view seemingly piled on top of each other, the car icons facing different directions. When I go to the spot in free roam, they are either derailed and pointing in random directions, all sitting on the same point, or not derailed and completely invisible, although I can
hear idling engines. I have no idea how this could be happening, there is no track leading to the point at which they are sitting in the derailed case.

Thanks for any help / explanation.

This is a bug that has been reported and being investigated. There are numerous iterations including having freight cars and locomotives corral around into a pinwheel shape in the middle of the route around the world origin. Your trains found your world origin on that route.

You need to edit the Session, not the saved driving session that you've been driving around, but I have found I can rescue these trains (consists) by placing a length of track nearby then clicking and dragging the consist back on to the piece of track. You can even try this by dragging the consist across the map to your route, but that maybe difficult depending upon how far away the consist is located.

Thanks, I hope a solution is found soon.