If I delete the locomotive, the station stops reading the contents of the wagons. Behind the scenes, this seems to be because deleting the loco causes the wagons to become part of a new train with a new id, and although that train still has the same schedule as the old one, with the same current stop, it is not in the stopped state because it was forced into manual mode upon creation.
I would like for this situation to result in the new train still being stopped at the station and readable.
This also fits together with my other recent request to allow snapping new wagons to stations, in that wagons placed like that should also be readable.