Why are some lines straight yet others take a bumpy segmented course?


I don't seem to have any control over the path chosen. It doesn't seem related to notes in the way (if I delete the notes on the path above, nothing changes).

UPDATE: I see that the paths change when the diagram is saved; they get rerouted around the notes. This is clever although it was not obvious. I've left this post in case somebody else is puzzled.