I have an Amtrak six-car passenger train on my layout---A.I Driven. Before, the train always stopped just past the station and the passenger cars working steps and doors would open to unload/load passengers at the loading dock. Then, just all of a sudden, the loco starts stopping right at the station loading dock and the cars are behind the station dock....sometimes the animated doors and steps work--sometimes not. I can't see anything different in my A.I. instructions. Anyone have a clue why it began stopping at the platform instead of driving on ahead like it used to?