My apologies, 0.17.79, LTN version 1.11.9. So the mk3 train and 4 mk3 wagons is set to a ltn depot. The LTN mod just will not dispatch them. Also the LTN stop output signal (next to the lamp at each signal) shows that it is trying to output signals( 30-encoded positions of every cargo wagon; 30-encoded positions of every.....mk3 wagon; encoded position of every locomotive; encoded position of every mk3 locomotive) That is with 1-4 trains. Also tried using just mk3 wagons with a vanilla loco, they still would not "dispatch"
I did not create those signals, and they do not show on any of my stations with vanilla trains.