@pmrrk Frankly, I've encountered the same thing once in awhile...I get to a point where uTorrent says I'm seeding but no data is going through after a certain limit.
It's likely because, once many others have snatched your torrent and are seeding, you may simply have a slower speed connection than they do, and so they become the primary seeders. I found this online:
Or you are a member of a private tracker with a ton of fast seeds (seedboxes etc) and the peers with a small connection meet difficulties to upload especially when the number of seeders per torrent is really huge in comparison with the number of leechers.
Basically, there's probably nothing you can do about this situation if enough others with better or faster connections are seeding. I think also especially if there are no leechers downloading (I've noticed this same thing also), then later on leechers hop onboard. You get "ignored" in favor of the people with better connections who are seeding.