I use multi-stations for delivering items (both regular and mixed). If I set the threshold as a number (for a two-car train, I use -4000), everything works fine.
However, when I set the threshold in stacks (for the same train, I use -76, but I've tried different values), there are no cargo deliveries. However, sometimes, as it seemed to me, the train does arrive, but in general, the request stations do not work if the stack threshold is set. The station is definitely assembled correctly, since switching the threshold to a number (and changing its value) immediately starts the station up and running.