You can also use this command here:
<kuid2:368725:60011:3> InstantLoad with a product from a queue specified by the user.
As part of the driver commands that activate once a train exits the portal. I use this method to instant load locos and passengers with no issues at all. I recommend putting in a wait command prior to give the AI a chance to gather its sea legs once the consist exits the portal. I did notice that the wait command helps to get the AI settled in first. I use 20 seconds for that, so the AI exits, sits for 20 seconds, loads the commands it has to then drives off.