I'm running the same version in a vm as well as 3.13 26837 in another. Seeding ~900+ torrents in both with no issues. Likely not utorrent but something in your setup or OBT. Try using/adding some other udp trackers. IFar
It's the way uTorrent handles magnet link. The devs are working/thinking about changing how the links are handled. Using the search function here in the forums and putting in +magnet +files you'll see the topic has been beaten to death IFar