Hello Harry,
Among your sidings to be worked, would the Springfield Junction South Main or North Main be among them?
Usually in the TDBCSV file, the "A" designates that all cars are being called for or shipped out from, cars which are indicated in the CTP file. Normally an "A" with no other character in the CARTYPEWANTED or CARTYPESHIPPED column will select any type indicated in the CTP file.
I have noticed that for both sidings referred to (and they are the only ones for this issue), it has been found that the inscription "A" is being added by another type of car as seen in the screenshot of parts of the TDBCSV file including the referred sidings..
I am not sure of this being the source of the problem but it seems to suggest that the "A" character added with another car type loses its attribute of selecting any type of car and is being coinsidered a car type itself when added to another like shown here.
I am sure Norm or Steve will have their say in finding the problem