Hrmpf... No idea how I didn't see that, sorry and thank you very much.

Edit: Not a bug. Waiting trains are supposed to increase the path finding penalty of their block every tick. https://giant.gfycat.com/AbsoluteDamagedAcornweevil.mp4 https://gfycat.com/absolutedamagedacornweevil I have two train stops with the same name (transfer 1-1-1) and train limit of 1, and one ...

You could extend the last idea with the waiting station, and let the trains leave the waiting station only if the smelter has at least one free spot. Since the train will lock in the smelter station only after it is done with the waiting station, it should always pathfind only to the smelter of the ...