Well, it could blocking TCP/IP connection that somehow is persistent on localhost. We had a bug in Qt that didn't allow us to use MapboxGL with localhost while device was offline. To go around it, I had to build MapboxGL with libcurl instead of using Qt network libs. On OSMSS side, I still use Qt libs for parts in network stack (not much though).

*why* would be great to know, but that's a reason I am trying to eliminate parts. OSMSS and Pure Maps communicate via HTTP (MapboxGL) and DBus (map matching). Using Pure Maps online without map matching (ideally without OSMSS running at all) would drop DBus from the suspects list.

As for other components - take your pick: Pure Maps, pyotherside, Qt, Silica, to name few. I think we tried to debug it and get some backtraces, but we either didn't get any wiser or we didn't finish it.