Sometimes relationship lines are missing all symbols on the crows foot end (Barker) of the line. If I bring up the properties and change Transferability (maybe others) the line is drawn correctly. Lines that are missing crows feet sometimes redraw even after adding an elbow. When the line is redrawn the elbow is gone. If i figure out when this happens I will post more details.
I have seen that behavior in 3.3 as well. Seemed to be a memory related issue. I usually have to remove one of the object from the diagram then drag it back in to get "normal" behavior to return.