I was doing mission "RrRr----:RgRg----" and i did cut my green on red square without care about direction, it didn't load and goes to nexus (red train with jump into nexus).
after i did add left / right turners to get all pieces oriented the same direction it started to load into the train loader and arrival to the nexus.
that's all (i feel also that signal generators should consider not only the orientation and not only the shape model, but that is not a bug, that would just be a plus, but maybe it would overload the engine)
thanks for game it is awesome, you guy who made this game gameplay and ergonomic approach, you just master it, it's really impressive (20 years i'm playing rts and builders so i know what i'm speaking about), never saw that before.