Joe,

>suddenly have 2 cars whose current location is PS-12y which is a reporting point for industry SPOT PS-21 and PS-23. 

In the data you sent (thank you!), cars list-numbers 40 and 63 are at PS-12y.   This reporting point is used by a train, which is a turn that goes:

RVS-Yd -> PS-12y -> MN-12y -> PS-12y -> RVS-Yd

Because the train works PS-12y on both the outbound and inbound legs, the cars are only picked up from PS-12y on the inbound leg.   When the train is reported at MN-12y the cars are made extra (shown with a *).

I displayed the train-consist on leaving MN-12y, and a second time while the train was at PS-12y (the second time at that location).  Displaying the train-consist moved the cars from "extra car" status to being "in the train" status. 

When the train was reported back at RVS-Yd the cars were moved to RVS-Yd.   Verified by checking the list of cars in the yard.

~~~

You have PS-12y set up properly, with a 10-ft capacity.  This should prevent any cars from being setoff at PS-12y.

I do have a suggestion:  that train, MNT-1, has what appears to be a low tonnage limit.   The car limit is 10, and 10 >loaded< cars would weigh out at about 1000 tons (in your era).  Plus the assigned engine.   I would be tempted to up the tonnage.  Did you have a reason for going to the lower tonnage limit?

If you see cars being setoff at one of your reporting pelase let me know.

            Jim