Journey Planner - what am I doing wrong?

Everyone likes a Christmas puzzle, so … what’s going on here?

This is my JP search:-
Tottenham Court Road Station to Canada Water Bus Station, bus-only, fewest changes, now.
Expected result: bus 1
Actual result: 390 to Victoria, C10 to Rotherhithe Station and walk.
The 1 timetable is available because it comes up as the third bus if I make the destination Southwark Park Road instead. There are no status updates for the route and Countdown doesn’t suggest any problems.

The Google API also comes up with 11 stops on the 188 and a short walk.