Train Sim World 3 Trouble Completing Barstow Yard Switching 1

I've tried this timetable service several times. This time, I thought I could complete it: as I approached my final stopping point, the F9 route map showed the final switch set in my favor:
However, looking at the front camera view, that is not the case:

The switch just ahead of me had been changed to accommodate a higher priority train that had some up behind me! (Sorry, I didn't take a screenshot showing both trains.)

I've tried to drive this session several times, always ending up with this situation. Suggestions welcome!

 

I don't own the route so this is just a hunch, but is it possible for you to voluntarily give way to the train behind you by waiting outside the signal block? Also that map image doesn't show the setting of the switch at all because it is an automatic switch, only the required path for you. This is most noticeable in a yard with manual switches where the blue line is still present even if the switch is pointing the wrong way.

 

That is an interesting story you had there, but I am sorry it didn't work.

Have you tried possibly waiting for the train to go into the siding with you waiting behind it? Perhaps the signaller wants the AI train to go first? Do you have an opportunity after the arrival of the AI train and before it reverses to go to the destination?

Hang on did they fix save games? I know the option is back now, but have they been fixed for this route? Perhaps that train was pathed before you, even though you were in front of it!

 

I've had something like this happen when I was too slow during a scenario. Don't remember the route/train, but I managed to complete it when I was quicker.

 

I think you have to wait for the AI train after your second decoupling.

At some point you're asked to decouple 13 wagons; when this happens you need to wait. After several minutes you'll see an AI train pass you on he track immediately to your right. Once it's gone, set the switches and follow the instructions.

If you're too slow, the AI train will follow you as described by OP and there's no way to complete the mission (that I know of). If you're too quick, you'll hit a red light near OP's screenshot, and the AI train will also hit a red light a few meters in front of you; if this happens, reverse back to your siding and wait for the AI train to pass.