I'm having the same 'not seeding' situation.. I completed download and left Transmission (on Mac pro) on for days.. When I check my seeding stats. the server says it is seeding, but i guess nobody is downloading.. I can leach and seed on any number of sights,,Anounamouse, Kickass Torrents, mac torrents, pirate bay, etc.
Any instructions for Transmission would be helpful..I couldn't find any.
thanx angelonyc