Currently PathSegment.addPattern() always uses the pattern with most stops. This is usually good, but not always. If there are two different routes between the start and end point, especially with big geographical deviations, only the longer gets rendered.
Example, two different patterns on one journey from A to D:
[A] -> ---- [B] ---> [C] -> [D]
\ [E] -> [F] -> [G] /
Transitive always renders only the rote A-E-F-G-D, even if it would have just one departure and A-B-C-D would have multiple departures.