This is not a Marble error but error in Openstreetmap database. I looked the map data and there is lots of overlapping/duplicate roads that some are missing the connection between them. I tried to clean it up ... However, I think I did correct it enough so that once the database is updated your routing problem is gone.
If you are interested in fixing similar problems in this area, you should consider opening account at openstreetmap.org and edit the map by yourself.